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Troposphere

The troposphere is the lowest and densest layer of Earth's atmosphere, extending from the planet's surface to an average altitude of about 12 kilometers (7.5 miles), and it contains the air essential for life, including the oxygen humans and animals breathe.^[1] This layer, derived from the Greek word tropos meaning "turning" or "mixing," is characterized by constant turbulent motion due to convection and weather systems, with temperatures decreasing with height at an average environmental lapse rate of approximately 6.5°C per kilometer.^[2] It holds roughly 75–80% of the total atmospheric mass, making it the most substantial portion of the atmosphere by weight.^[3] The height of the troposphere varies significantly with latitude and season, reaching up to 18–20 kilometers at the equator due to stronger solar heating and convection, while thinning to about 6 kilometers at the poles where cooler temperatures limit vertical mixing.^[4] Almost all weather phenomena, including clouds, precipitation, storms, and wind patterns, occur within this layer because it encompasses about 99% of the atmosphere's water vapor and aerosols, which drive these dynamic processes.^[5] The troposphere's composition is primarily dry air consisting of 78% nitrogen, 21% oxygen, and 1% other gases like argon and carbon dioxide, though water vapor content can vary from near 0% in polar regions to up to 4% in humid tropical areas.^[1] This layer serves as the interface between Earth's surface and the rest of the atmosphere, influencing climate through the absorption of solar radiation and emission of terrestrial heat, while also hosting human activities such as aviation and agriculture.^[4] Above the troposphere lies the tropopause, a transitional boundary where temperature stabilizes, marking the shift to the stratosphere.^[5] Changes in tropospheric conditions, such as those driven by greenhouse gases, can amplify global warming effects by altering water vapor feedback and heat distribution.^[6]

Overview

Definition and Characteristics

The troposphere is the lowest layer of Earth's atmosphere, extending from the planet's surface upward to the tropopause, and it serves as the primary region for atmospheric convection and nearly all weather phenomena. This layer encompasses the air essential for life, including the oxygen humans and animals breathe and the water vapor that drives cloud formation and precipitation. The term "troposphere" was coined in 1902 by French meteorologist Léon Teisserenc de Bort, derived from the Greek "tropos," meaning turning or mixing, to highlight the layer's dynamic, convective motions.^[1]^[5]^[7] Key characteristics of the troposphere include its substantial mass and role in global atmospheric processes. It contains approximately 80% of the total atmospheric mass, making it the densest layer due to gravitational compression. Vigorous vertical mixing occurs here, driven by surface heating from solar radiation, which promotes the development of storms, winds, and other meteorological events. Adiabatic processes—where rising air expands and cools or descending air compresses and warms without net heat exchange—dominate because of this thorough mixing, shaping the layer's thermal structure.^[3]^[8] The troposphere is distinctly separated from the stratosphere above it by their opposing temperature profiles. While temperature in the troposphere generally decreases with altitude due to radiative cooling and convective overturning, the stratosphere experiences an increase in temperature with height owing to ultraviolet radiation absorption by ozone molecules. This thermal inversion at the tropopause marks a stable boundary that largely inhibits mixing between the two layers.^[9]

Vertical Extent and Variations

The troposphere extends from Earth's surface to varying heights depending on latitude, with an average thickness of about 11 km in mid-latitudes, increasing to 18-20 km near the equator and decreasing to 6–8 km at the poles.^[4]^[10] These latitudinal differences arise primarily from uneven solar heating, which drives more intense vertical convection in tropical regions, expanding the layer, while colder polar temperatures promote stable air masses that compress it.^[11]^[12] Seasonal fluctuations further modify the troposphere's extent, with heights typically lower by 1-2 km in winter due to reduced solar insolation and higher in summer from enhanced heating and convection.^[10] Earth's rotation contributes through the Coriolis effect, influencing large-scale circulation patterns like the Hadley cells that sustain stronger upward motion and greater thickness in the tropics compared to the subsidence and stability in polar areas.^[13]^[14] The vertical extent is measured using several techniques, including radiosondes launched from weather balloons that provide direct temperature and pressure profiles to identify the tropopause boundary.^[15] GPS radio occultation from satellites like COSMIC derives height from atmospheric refractivity profiles with high precision.^[16] Satellite lidar systems, such as those on CALIPSO, contribute by detecting aerosol and cloud layers near the tropopause for indirect validation.^[17] These variations have practical implications for aviation, as commercial aircraft generally cruise at altitudes of 9-12 km within the upper troposphere to minimize encounters with turbulence and weather systems confined to lower levels.^[18]^[19]

Physical Structure

Atmospheric Composition

The troposphere's dry air is primarily composed of nitrogen (approximately 78% by volume), oxygen (21%), argon (0.93%), and carbon dioxide (about 0.04%), along with trace gases such as neon, helium, methane, and krypton.^[20]^[21] These proportions remain relatively uniform throughout the troposphere due to mixing processes, though trace components can vary regionally.^[22] Water vapor introduces significant variability to the tropospheric composition, ranging from 0% to 4% by volume and constituting the most abundant greenhouse gas after carbon dioxide.^[23]^[20] Concentrations are highest near the Earth's surface, where they can reach up to 4% in humid tropical regions, and decrease rapidly with altitude, often dropping below 0.1% above 5 km.^[24] Unlike the drier upper atmosphere, the troposphere's water vapor facilitates extensive photochemical reactions, including the photolysis of ozone that generates hydroxyl radicals (OH), which drive the oxidation of pollutants and trace gases.^[25]^[26] Tropospheric gases originate from both natural and human sources, with sinks primarily through deposition processes. Biogenic emissions, such as volatile organic compounds (VOCs) from vegetation, contribute significantly to reactive hydrocarbons, while anthropogenic pollutants like nitrogen oxides (NOx) from combustion and sulfur dioxide (SO2) from industrial activities add to the reactive nitrogen and sulfur budgets.^[27]^[28] Removal occurs via wet deposition (rainout and washout) and dry deposition (surface uptake), which act as major sinks for soluble gases like nitric acid and sulfuric acid.^[29] Carbon dioxide levels in the troposphere have risen notably since 2020, reaching approximately 426 ppm by November 2025, driven by ongoing anthropogenic emissions from fossil fuel combustion and deforestation.^[30] Enhanced monitoring by satellites such as NASA's Orbiting Carbon Observatory-2 (OCO-2) has improved quantification of these regional sources and sinks, revealing hotspots over urban and industrial areas.^[31]

Pressure and Density Profiles

The vertical distribution of pressure and density in the troposphere is primarily governed by hydrostatic equilibrium, a condition where the downward force of gravity on an air parcel is balanced by the upward pressure gradient force. This balance is described by the hydrostatic equation \frac{dP}{dz} = -\rho g, where P is atmospheric pressure, z is altitude, \rho is air density, and g is the acceleration due to gravity (approximately 9.81 m/s² near the surface).^[32]^[33] As a result, both pressure and density decrease exponentially with increasing altitude, with the rate of decrease depending on local density and gravitational strength.^[34] The pressure profile in the troposphere can be approximated using the barometric formula under the assumption of isothermal conditions:

P(h) = P_0 \exp\left(-\frac{M g h}{R T}\right),

where P_0 is the sea-level pressure (typically 1013 hPa), M is the molar mass of dry air (0.02896 kg/mol), g is gravity, h is height above sea level, R is the universal gas constant (8.314 J/mol·K), and T is the average temperature.^[34]^[35] In practice, pressure drops from about 1013 hPa at sea level to roughly 200–220 hPa at the tropopause (around 11 km in mid-latitudes), reflecting the cumulative weight of the overlying atmosphere.^[36] This exponential decay ensures that over 75% of the tropospheric mass resides below 10 km.^[32] Air density follows a similar exponential decline, starting at approximately 1.225 kg/m³ at sea level under standard conditions and decreasing to about 0.36 kg/m³ at the 11 km tropopause level.^[37] This profile arises from the ideal gas law combined with hydrostatic balance, where density \rho = \frac{P M}{R T}, making it sensitive to both pressure reductions and temperature variations with height.^[2] Local temperature perturbations, such as those from urban environments, can thus modulate density slightly at given pressures.^[34] Reanalysis datasets like ERA5 from the European Centre for Medium-Range Weather Forecasts provide high-resolution insights into these profiles, revealing that urban heat islands induce minor local adjustments—typically on the order of 0.1–0.5% in near-surface density—due to elevated temperatures expanding air volumes under hydrostatic constraints.^[38] These variations are most pronounced in the lower troposphere and contribute to subtle shifts in vertical stability over urban areas.^[38]

Temperature Lapse Rate

The temperature in the troposphere decreases with increasing altitude, a process quantified by the environmental lapse rate, which represents the observed average rate of this decrease. Under standard conditions, this rate is approximately 6.5 °C per kilometer, resulting in a typical drop from about 15 °C at sea level to -56.5 °C at the tropopause around 11 km altitude.^[39] Theoretical lapse rates provide insight into the physical processes governing this gradient. The dry adiabatic lapse rate, applicable to unsaturated rising air parcels undergoing no heat exchange with surroundings, is 9.8 °C/km and derived from the first law of thermodynamics as \Gamma_d = \frac{g}{C_p}, where g \approx 9.8 m/s² is the acceleration due to gravity and C_p \approx 1004 J/kg·K is the specific heat capacity of dry air at constant pressure.^[40] The moist adiabatic lapse rate, relevant in humid conditions where condensation releases latent heat, is lower at about 5–6 °C/km on average in the tropics, as this heat release reduces the net cooling during ascent.^[41]^[42] The environmental lapse rate emerges from a balance of key mechanisms: surface heating initiates convection, mixing warmer air upward; radiative cooling predominates in the upper troposphere, enhancing the gradient; and large-scale convection transports heat vertically to maintain near-adiabatic conditions.^[43]^[44] Deviations occur occasionally, such as temperature inversions where the lapse rate becomes negative (temperature increases with height), typically under stable subsidence in high-pressure systems that compress and warm descending air.^[45] Observations from the 2020s, informed by climate models, reveal subtle shifts in the tropical lapse rate amid global warming, with projections indicating a slight decrease in the lapse rate magnitude (less steep) due to enhanced upper-tropospheric warming relative to the surface, contributing to the negative lapse rate feedback.^[46] These changes influence upper-tropospheric warming patterns and underscore the troposphere's sensitivity to anthropogenic forcing.^[47]

Humidity and Water Vapor

Water vapor concentration in the troposphere exhibits a pronounced vertical profile, reaching its highest levels near the Earth's surface where it can constitute up to 4% by volume in the warm tropics due to high evaporation rates from oceans and land.^[48] As altitude increases, the mixing ratio decreases rapidly, often dropping to near-zero values at the tropopause because of colder temperatures that limit the air's capacity to hold moisture.^[49] Within clouds, relative humidity typically approaches 100% saturation, enabling the formation and persistence of liquid or ice particles.^[50] Key processes governing water vapor in the troposphere include evaporation from surface water bodies, which introduces moisture into the lower atmosphere; condensation, where cooling air leads to the formation of cloud droplets; and precipitation, which removes excess vapor as rain, snow, or other forms when saturation is exceeded.^[51] These phase changes facilitate the vertical and horizontal transport of water, maintaining the troposphere's dynamic hydrological balance. Water vapor also serves as the most abundant greenhouse gas in the troposphere, absorbing infrared radiation emitted from the Earth's surface and lower atmosphere, thereby trapping heat and contributing significantly to the planet's energy budget.^[6]^[52] The distribution and amount of water vapor are fundamentally linked to temperature through the Clausius-Clapeyron relation, which describes how saturation vapor pressure increases with warming. An empirical approximation for this is given by the Tetens formula:

e_s \approx 6.11 \times 10^{\frac{7.5T}{237.3 + T}} \quad \text{hPa},

where T is temperature in °C; this relation implies that the atmosphere's capacity for water vapor grows by approximately 7% per 1°C of warming, amplifying moisture availability and related processes in a changing climate.^[53]^[54] Observations indicate a tropospheric water vapor increase of about 5% globally since 2000, driven primarily by rising temperatures that enhance evaporation and atmospheric holding capacity, consistent with water vapor feedback mechanisms outlined in recent assessments.^[55]^[56]

Upper Boundary

Tropopause Characteristics

The tropopause serves as the upper boundary of the troposphere, representing a transitional zone where the decrease in temperature with altitude ceases, signifying the end of the region dominated by convective processes. This boundary marks the shift to the stratosphere, where stability inhibits vigorous vertical mixing characteristic of the troposphere below. Globally, the tropopause is located at an average altitude of 11–14 km.^[4] Thermally, the tropopause functions as a cold trap, with temperatures typically ranging from -50°C to -70°C, which effectively restricts the ascent of water vapor and other constituents into the stratosphere by promoting dehydration through freezing and sedimentation. This low-temperature regime establishes a stable layer that acts as a barrier to large-scale vertical mixing, confining most tropospheric dynamics and weather phenomena to the layers below.^[57] Two primary conceptual types of the tropopause are distinguished based on underlying physical processes: the convective tropopause, often identified as the top of the convective layer where the atmosphere transitions from convectively adjusted to radiatively controlled, typically near the level where deep convection ceases due to stability; and the radiative tropopause, defined by the level where radiative heating—primarily from ozone absorption of ultraviolet radiation—induces a temperature minimum and subsequent inversion.^[58] The most widely used detection method for the tropopause relies on thermal criteria established by the World Meteorological Organization (WMO), which defines it as the lowest altitude at which the lapse rate decreases to 2°C/km or less, provided the average lapse rate between this level and 2 km above does not exceed 2°C/km.^[59]

Tropopause Variations

The tropopause height exhibits significant latitudinal variations, reaching approximately 16 km in the tropics where it is also colder, typically around 190–195 K, compared to about 8–9 km in polar regions with warmer temperatures of 210–220 K.^[58] This gradient reflects the influence of mean tropospheric temperatures, which are higher in the tropics due to intense solar heating and convection. A distinct subtropical tropopause break occurs around 30° latitude, marking a sharp transition from the elevated tropical tropopause to the lower extratropical one, associated with the position of the subtropical jet stream.^[60]^[61] Seasonal cycles in tropopause height are driven primarily by hemispheric heating patterns, with the boundary rising by 2–4 km in summer due to enhanced tropospheric warming and convection, particularly in the extratropics where it can exceed 14 km.^[62] In contrast, during winter, the tropopause lowers and becomes more dynamic, often featuring folds during storm systems that facilitate stratosphere-troposphere exchange.^[63] Diurnal variations remain minimal globally, typically less than 0.5 km, though slight elevations occur during daytime in convective regions due to localized heating.^[64] External influences such as jet streams induce localized tropopause folding and pockets, particularly along the polar and subtropical jets, where intrusions of stratospheric air into the troposphere can depress the boundary by 1–2 km over synoptic scales.^[63] Volcanic eruptions, like the 2022 Hunga Tonga–Hunga Ha'apai event, temporarily perturb the tropopause through massive injections of water vapor (over 150 Tg) and aerosols that breach the boundary, enhancing tropopause temperatures for months afterward.^[65]^[66] Recent satellite observations, including data from the Microwave Limb Sounder (MLS) on NASA's Aura satellite, indicate a long-term upward trend in tropopause height of approximately 100–200 m per decade in many regions, attributed to anthropogenic tropospheric warming that expands the layer below the stable stratosphere.^[67] This rise, most pronounced over the Northern Hemisphere since the 1980s, underscores the tropopause's sensitivity to climate change, with implications for atmospheric circulation and trace gas distributions.^[68]

Atmospheric Dynamics

General Circulation Models

The three-cell model describes the large-scale meridional circulation of the troposphere, dividing each hemisphere into three distinct overturning cells that transport heat and momentum from the equator toward the poles. In this idealized framework, air rises in regions of excess solar heating and sinks where cooling dominates, creating closed loops of vertical and horizontal motion that span the depth of the troposphere. The model assumes an aquaplanet with zonally symmetric heating, providing a foundational understanding of global atmospheric dynamics. The Hadley cell operates between approximately 0° and 30° latitude in both hemispheres, characterized by intense solar heating at the equator that drives air ascent near the Intertropical Convergence Zone (ITCZ), followed by poleward flow aloft and subsidence in the subtropical highs around 30°. This thermally direct circulation efficiently redistributes equatorial heat toward higher latitudes. The Ferrel cell, spanning 30° to 60° latitude, is an indirectly driven mid-latitude cell where surface westerlies prevail, with air rising near 60° and sinking near 30°; its motion is maintained by interactions with the adjacent cells rather than direct thermal forcing. The Polar cell, from 60° to 90° latitude, features cold air sinking at the poles and rising around 60°, completing the poleward heat transport in a smaller, thermally direct loop.^[69]^[70] These cells are primarily driven by the latitudinal gradient in solar heating, which creates a surplus of energy at the equator and a deficit at the poles, initiating meridional flows to balance the imbalance. The Coriolis effect, arising from Earth's rotation, deflects these flows to produce the observed wind patterns, while conservation of angular momentum accelerates poleward-moving air aloft, contributing to the subtropical jet streams.^[69]^[71] The conceptual basis of the three-cell model traces back to George Hadley, who in 1735 proposed a single-cell circulation driven by equatorial heating and trade winds. William Ferrel expanded this in 1856 by incorporating the Coriolis effect to explain mid-latitude westerlies, introducing the indirect Ferrel cell as part of a multi-cell system.^[69]^[72] Modern general circulation models (GCMs) build on this framework by incorporating longitudinal asymmetries, such as the Walker circulation—a zonal overturning cell in the tropical troposphere featuring ascent over the warm western Pacific and subsidence over the eastern Pacific, superimposed on the Hadley cell to explain east-west variations in trade winds. GCM simulations further reveal climate change impacts, including a poleward expansion of the Hadley cell by 1–3° latitude per degree of global warming, driven by stratospheric ozone depletion and greenhouse gas increases, as projected in Coupled Model Intercomparison Project Phase 6 (CMIP6) ensembles through 2025. These shifts alter subtropical dryness and storm tracks, with the Ferrel and Polar cells showing more variable responses.^[73]^[74]^[75]

Zonal and Meridional Flows

In the troposphere, zonal flow refers to the east-west component of atmospheric circulation, dominated by westerly winds in the mid-latitudes (30°–60° latitude). This prevailing westerly direction arises from thermal wind balance, where the equator-to-pole temperature gradient induces a vertical shear in the zonal wind, with speeds increasing toward the upper troposphere due to the Coriolis effect and geostrophic adjustment.^[76] The thermal wind relation, derived from hydrostatic and geostrophic balance, quantifies this shear as proportional to the meridional temperature gradient, ensuring stronger westerlies aloft to balance the cooler polar air masses.^[77] The most intense zonal flows manifest as subtropical and polar jet streams, narrow bands of accelerated westerlies near the tropopause at altitudes of 10–12 km, with core speeds typically ranging from 200 to 300 km/h (50–80 m/s). These jets form at the boundaries of major circulation cells, driven by angular momentum conservation and baroclinicity, and play a key role in guiding mid-latitude weather systems. Meridional flow, the north-south component, contrasts with zonal dominance by exhibiting weaker but crucial poleward transport in the upper troposphere and equatorward return in the lower troposphere, facilitating global heat redistribution. In the upper levels, air rises over warm equatorial regions and flows poleward, while cooler air sinks and moves equatorward near the surface, consistent with the three-cell model of atmospheric circulation. This pattern encompasses seasonal monsoon systems, where intense low-level equatorward moisture influx from oceans feeds upper-level poleward outflows over heated continents, and mid-latitude storm tracks, where baroclinic eddies enhance meridional momentum and heat fluxes through transient cyclones.^[78]^[79] Interactions between zonal and meridional flows are modulated by Rossby waves, large-scale undulations in the westerly jets that propagate eastward and introduce meridional meanders, amplifying north-south exchanges. These waves, governed by the beta effect from Earth's rotation, can grow through baroclinic instability, leading to amplified troughs and ridges that foster blocking highs—quasi-stationary anticyclones which impede zonal progression and prolong regional weather patterns.^[80] Recent studies as of 2025 suggest a weakening of the jet stream attributed to Arctic amplification, which diminishes the meridional temperature gradient and weakens the thermal forcing for zonal acceleration.^[81] However, the link remains debated, with some 2025 studies suggesting that erratic jet stream behavior predates significant Arctic warming.^[82]

Role and Impacts

Weather and Climate Influence

The troposphere serves as the primary arena for Earth's weather phenomena, where processes such as convection, the formation of fronts, and the development of cyclones and anticyclones are confined due to the tropopause acting as a stable boundary layer that inhibits vertical mixing beyond approximately 10-15 km altitude.^[4] Convection, driven by surface heating, initiates rising air parcels that lead to cloud formation and precipitation, while fronts—boundaries between contrasting air masses—trigger instability and storm development within this layer.^[83] Cyclones, characterized by low-pressure systems and inward spiraling winds, and anticyclones, their high-pressure counterparts with outward flows, dominate mid-latitude weather patterns, often producing widespread rain, wind, and temperature shifts entirely below the tropopause.^[84] Thunderstorms exemplify intense tropospheric activity, with powerful updrafts capable of penetrating the tropopause, forming anvil-shaped clouds that spread outward and marking the layer's upper limit.^[85] Tropospheric dynamics play a crucial role in climate regulation by facilitating the redistribution of heat from the equator toward the poles through large-scale convection and circulation patterns, balancing the planet's uneven solar energy input.^[86] This meridional transport prevents excessive equatorial warming and polar cooling, maintaining global temperature gradients essential for stable climate conditions. Additionally, water vapor within the troposphere acts as a potent feedback mechanism, amplifying greenhouse warming; as temperatures rise due to CO₂ increases, higher evaporation loads the atmosphere with more water vapor, which traps additional heat and roughly doubles the direct warming effect from CO₂ alone.^[87]^[88] Long-term tropospheric warming has contributed to an uptick in extreme weather, particularly intensified precipitation events, as warmer air holds more moisture per the Clausius-Clapeyron relation, fueling heavier downpours during storms. For instance, in the United States, the amount of rainfall in the most intense precipitation events has risen by about 20% since the early 1900s, a trend linked to observed tropospheric temperature increases.^[89] Globally, the frequency and intensity of heavy precipitation have escalated since the 1950s over most land areas with sufficient data, heightening risks of flooding and related disruptions.^[90] The troposphere's influence extends to major climate oscillations like El Niño and La Niña, where shifts in the Walker circulation—a zonal tropospheric wind pattern—alter convection and heat distribution across the Pacific. During El Niño, weakened easterly trade winds suppress the Walker cell, displacing warm waters eastward and enhancing upper-tropospheric heating through anomalous convection, which amplifies global temperatures. The 2023-2024 El Niño event, one of the strongest on record, exemplifies this, driving record-high global surface and upper-tropospheric temperatures through intensified heat release and circulation anomalies, with lingering effects into 2025 before the onset of La Niña conditions.^[91]^[92]

Human and Environmental Interactions

Human activities significantly alter the troposphere through emissions of pollutants, positioning it as a primary sink for aerosols and ozone precursors derived from both anthropogenic and natural sources. These emissions, including nitrogen oxides (NOx) and volatile organic compounds (VOCs), undergo photochemical reactions in the troposphere to form ground-level ozone and secondary aerosols, contributing to urban smog formation. Similarly, sulfur oxides (SOx) react with water vapor and other tropospheric constituents to produce sulfuric acid, which combines with nitric acid from NOx to form acid rain that deposits back to Earth's surface. Such pollution processes are exacerbated in urban areas, where high concentrations of precursors lead to elevated aerosol optical depths and reduced air quality. Aviation activities introduce additional human-induced changes, as aircraft exhaust in the upper troposphere generates persistent contrails that spread into cirrus clouds, enhancing cloud cover and contributing approximately 1% to total anthropogenic radiative forcing through trapping of outgoing longwave radiation. Tropospheric ozone levels have also risen due to increased precursor emissions, with global trends showing an average increase of about 0.5 Dobson Units (DU) per decade since the 1990s, amplifying the greenhouse effect and surface warming. These changes, while interconnected with broader atmospheric composition shifts, underscore the troposphere's role in mediating human-driven climate perturbations. To mitigate these interactions, weather forecasting systems heavily rely on tropospheric models that simulate pollutant dispersion, ozone formation, and dynamic processes for accurate predictions. The European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System, for instance, incorporates tropospheric chemistry modules to forecast ozone and aerosol distributions up to 10 days ahead, aiding in air quality alerts and disaster preparedness. Space weather effects on the troposphere remain minimal, though intense solar storms can indirectly influence the upper troposphere by altering ionospheric conductivity and potentially enhancing precipitation patterns through cosmic ray modulation. Recent developments highlight ongoing efforts to address tropospheric buildup of precursors like methane, which indirectly boosts ozone formation via hydroxyl radical scavenging. In 2025, the United Nations Environment Programme (UNEP) advanced the Global Methane Pledge through the Climate and Clean Air Conference, targeting a 30% reduction in emissions by 2030 to curb tropospheric ozone and short-lived climate pollutants, with new frameworks for monitoring in the oil and gas sector. Post-COVID-19 lockdowns demonstrated rapid tropospheric recovery, with global nitrogen dioxide levels dropping 20-30% in 2020 before rebounding to pre-pandemic highs by 2022-2023 as economic activity resumed, emphasizing the reversibility of anthropogenic pollution impacts.

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This equation is the hydrostatic equation, which describes a change of atmospheric pressure with height.Missing: troposphere | Show results with:troposphere
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1.9: Hydrostatic Equilibrium - Geosciences LibreTexts
Dec 14, 2024 · The mass m of air in the slice equals the air density times the slice volume; namely, m = ρ · (A·Δz), where Δz is the slice thickness. For ...Missing: troposphere | Show results with:troposphere<|control11|><|separator|>
[34]
[PDF] CHAPTER 2. ATMOSPHERIC PRESSURE - Projects at Harvard
For a mean atmospheric temperature T = 250 K the scale height is H = 7.4 km. The barometric law explains the observed exponential dependence of P on z in ...
[35]
Barometric formulas: various derivations and comparisons to ...
Apr 4, 2020 · In this equation, p(h) is the atmospheric pressure at altitude h, p0 is the atmospheric pressure at sea level, g is the gravitational ...
[36]
[PDF] The Earth's Atmosphere-II - CalTech GPS
nearly 14.7 pounds. • Normal atmospheric pressure near sea level is close to ... • Tropopause (the top of the troposphere) at ~ 8-12 km, 220 hPa. – 78 ...
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U.S. Standard Atmosphere: Temperature, Pressure, and Air ...
A standard atmosphere can be regarded as an average pressure, temperature and air density for various altitudes.
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Insights Into Urban Heat Island and Heat Waves Synergies ...
Jul 3, 2024 · Our analysis, combining observations and simulations, confirms that heat waves worsen UHI effects. During heat waves, temperature differences ...2 Method And Data · 3.2 Urban Heat Island Effect... · 3.2. 2 Urban Heat Island...
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[PDF] The International Standard Atmosphere (ISA)
The temperature remains at a constant value of -56.5°C (216.65°K) from the tropopause up to 20,000 m (65,600 ft). This ISA model is used as a reference to ...
[40]
[PDF] Dry Adiabatic Temperature Lapse Rate - atmo.arizona.edu
Combining (13) with either equation (2) or (4) from the gravity and geopotential derivation above, yields. −g dz = CpdT. (14). So. dT dz. = − g. Cp. (15). This ...
[41]
Lapse Rate - an overview | ScienceDirect Topics
Lapse rate is the rate of temperature decrease with height in the atmosphere. If we consider the hypothetical case of a bubble of air rising through a dry ...Climate Dynamics · Exercise 10.1 · 13.2. 2 Convective Indices...<|separator|>
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Moist Adiabatic Lapse Rate - Lifestyle → Sustainability Directory
Oct 24, 2025 · A lower lapse rate generally implies a more stable atmosphere in the upper troposphere, which can act as a negative feedback on surface ...
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[PDF] Climate Modeling Through Radiative-Convective Models
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[44]
[PDF] Temperature Trends in the Lower Atmosphere - NOAA
The tropopause pressure level is defined by the standard lapse rate criterion: it is identified by the lowest level (above 450 hPa) where the temperature lapse.Missing: NASA | Show results with:NASA
[45]
Temperatures - The Inversion
As air sinks it warms adiabatically. Sinking air will warm at the dry adiabatic lapse rate due to the air being unsaturated. When high pressure promotes ...<|separator|>
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Changes in the Tropical Lapse Rate due to Entrainment and Their ...
Sep 7, 2021 · The tropical temperature in the free troposphere deviates from a theoretical moist-adiabat. The overall deviations are attributed to the entrainment of dry ...Introduction · Modeling Convection · LR Effects on Climate Sensitivity · Conclusions
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Future summer warming pattern under climate change is affected by ...
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Variations of Tropical Lapse Rates in Climate Models and Their ...
Abstract. The vertical temperature structure in the tropics is primarily set by convection and therefore follows a moist adiabat to first order.
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troposphere - UCSB Physics
The troposphere is wider at the equator (10mi) than at the poles (5mi). The troposphere contains 75 percent of atmosphere's mass- on an average day the weight ...Missing: authoritative source
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GML Water Vapor - Global Monitoring Laboratory - NOAA
Most relevant to our study is water vapor's effects on the Earth's energy budget, influencing both the incoming solar radiation and outgoing heat (IR).Missing: mass percentage
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[PDF] The Climatology of Relative Humidity in the Atmosphere
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The water cycle | National Oceanic and Atmospheric Administration
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[PDF] water vapor feedback and global warming
Oct 16, 2000 · To the extent that water vapor concentrations increase in a warmer world, the climatic effects of the other greenhouse gases will be amplified.Missing: AR6 | Show results with:AR6<|separator|>
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[PDF] Vapor Pressure
Then, saturated vapor pressure and the actual vapor pressure can be. (e )s. (e) calculated using the formula listed below: 6.11 10 e = ×. ( 7.5 × Td. 237.3 + Td ).Missing: Clausius- Clapeyron
[55]
What a 190-year-old equation says about rainstorms in a changing ...
Mar 30, 2023 · Meteorologists use the Clausius–Clapeyron equation to understand when water vapor will condense to liquid. That happens at what's called the ...Missing: troposphere | Show results with:troposphere
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Increase in Tropospheric Water Vapor Amplifies Global Warming ...
Jul 6, 2023 · The troposphere contains approximately 99% of the atmospheric water vapor, which plays a crucial role in Earth's climate system. It is at the ...
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Chapter 7: The Earth's Energy Budget, Climate Feedbacks, and ...
Since AR5, the effect of the water vapour increase in the stratosphere as a result of global warming has been investigated by different studies. This increase ...
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[PDF] Climatological characteristics of the tropical tropopause as revealed ...
A second thermal definition of the tropopause is the location of the coldest point in the temperature sounding, which we will refer to as the cold-point ...
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[PDF] Models for Tropopause Height and Radiative-Convective Equilibrium
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[PDF] Determining the tropopause height from gridded data
Methodology According to the WMO [1957], the tropopause is defined as ''the lowest level at which the lapse-rate decreases to 2°C/km or less, provided that the ...Missing: characteristics | Show results with:characteristics
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[PDF] Variability and trends in the global tropopause estimated from ...
Tropopause height trends over 1980–2004 are upward at almost all of the (predominantly extratropical) stations analyzed, yielding an estimated global trend of ...
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Characteristics of the subtropical tropopause region based on long ...
Sep 19, 2013 · [1] This study examines the structure of the subtropical tropopause region over Tenerife (the Canary Islands, Spain; 28°N, 16°W) based on a ...
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Annual cycle of the tropopause height - MeteoSwiss
The tropopause height peaks in late summer (around 12,000m) and is lower in winter/spring (10,500-11,000m), with over 15km possible in summer.Missing: rise folds
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Tropopause folds in ERA‐Interim: Global climatology and relation to ...
Apr 29, 2015 · Tropopause folds are intimately linked to upper level frontogenesis and jet stream dynamics. They play an important role for ...Abstract · Introduction · Characteristic Examples · Linkage With Extreme Weather...
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Seasonal and Diurnal Variations of Tropical Tropopause Layer (TTL ...
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[66]
Impact of Hunga Tonga-Hunga Ha'apai Volcanic Eruption on ... - MDPI
Jul 19, 2023 · Volcanic eruptions via volcanic aerosols enhance tropopause temperatures, permitting direct injection of water vapour into stratospheric ...
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The Estimated Climate Impact of the Hunga Tonga‐Hunga Ha'apai ...
Sep 26, 2023 · Following the January 2022 Hunga-Tonga eruption, both aerosols and water vapor increased in the stratosphere · The stratospheric water vapor ...
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[PDF] Global tropopause altitudes in radiosondes and reanalyses - ACP
Most trends point to an increase in tropopause alti- tude over time, with the largest increases (100–200m per decade) found over western China, the ...
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Continuous rise of the tropopause in the Northern Hemisphere over ...
Nov 5, 2021 · Variability in tropopause height is closely related to the thermal structure below and above (5, 8, 32). On the monthly scale (Fig. 2A), monthly ...
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Global Atmospheric Circulations - NOAA
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Wind Systems | manoa.hawaii.edu/ExploringOurFluidEarth
There are three circulation cells: the Hadley cell ... Thus, the Ferrel cell is like an atmospheric gear driven by the Hadley and polar circulation cells.<|control11|><|separator|>
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Chapter 11: General Circulation – Atmospheric Processes and ...
The general circulation also serves as a model for how heat and momentum are transported from the equator to the poles. ... Three-cell model of the rotating Earth ...Missing: driving | Show results with:driving
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Ferrel cell | Atmospheric Circulation, Global Wind Patterns & Jet ...
Ferrel cell, model of the mid-latitude segment of Earth's wind circulation, proposed by William Ferrel (1856). In the Ferrel cell, air flows poleward and ...
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The Walker Circulation: ENSO's atmospheric buddy - Climate
Aug 1, 2014 · ENSO can affect this atmospheric circulation, the Walker Circulation, over the entire tropics, impacting rainfall near the equator across multiple continents.
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The Hadley circulation in a changing climate - Lionello - 2024
Mar 26, 2024 · A key result is that both theory and models support the future expansion of the Hadley circulation under anthropogenic climate change.
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Recalibrated projections of the Hadley circulation under global ...
Sep 6, 2024 · Climate models project a weakening and expansion of the Hadley circulation (HC) under global warming but with considerable spread in the magnitude of these ...
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[PDF] Chapter 8 The general circulation of the atmosphere - Weather and ...
a zonal flow in thermal wind balance with the temperature gradient: since T decreases poleward, Eq.(7.24) implies westerly winds increasing with height.
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[PDF] Meteorology for Scientists and Engineers
Baroclinicity (i.e., the north-south temperature gradient) drives the west-to-east winds near the top of the troposphere, via the thermal wind relationship.
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[PDF] Chapter 5 The Meridional Structure of the Atmosphere
Fig. 5.21 shows the zonal-mean circulation of the atmosphere in the merid- ional plane – the meridional overturning circulation in height and latitude, whose ...
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General features of the seasonally varying mean circulation
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Atmospheric blocking as a traffic jam in the jet stream | Science
Atmospheric blocking due to anomalous, persistent meandering of the jet stream often causes weather extremes in the mid-latitudes. Despite the ubiquity of ...
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Evidence linking rapid Arctic warming to mid-latitude weather patterns
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Weather Processes and Systems | Earth Science - Lumen Learning
Explain how air masses and weather fronts together form mid-latitude cyclones. Describe the three phases a thunderstorm goes through in it's life cycle.
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[PDF] Chapter 12 - Weather Theory
At the top of the troposphere is a boundary known as the tropopause, which traps moisture and the associated weather in the troposphere.
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The Anatomy of a Thunderstorm - NASA Earth Observatory
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How Much More Will Earth Warm? - Global Warming
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Global warming frequently asked questions | NOAA Climate.gov
Oct 29, 2020 · This water vapor feedback loop is powerful, at least doubling the warming provided by carbon dioxide alone.
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A Climate of Extreme Weather Events
For example, the amount of rain that falls during intense precipitation events has increased by 20 percent in the United States over the last century. Over the ...Missing: tropospheric | Show results with:tropospheric
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Chapter 11: Weather and Climate Extreme Events in a Changing ...
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January 2025 update: La Niña is here | NOAA Climate.gov
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The 2023/24 El Niño event exhibited unusually weak extratropical ...
Jul 28, 2025 · Typically, the weakened Walker circulation during El Niño ... Enhanced risk of record-breaking regional temperatures during the 2023–24 El Niño.