Fact-checked by Grok 2 weeks ago

Okta

An okta is a in used to describe the amount of observed from a particular location. One okta represents one-eighth (1/8) of the sky , with the ranging from 0 oktas (clear sky) to 8 oktas (fully or obscured sky). The term is also spelled "octa", and the plural form is "oktas".

Definition and Measurement

Scale and Terminology

The okta (plural: oktas) is a in that quantifies the amount of by dividing the visible celestial dome into eight equal parts, each representing one-eighth of the . This scale ranges from 0 oktas, denoting a completely clear with no cloud coverage, to 8 oktas, indicating full overcast conditions where the entire is covered without breaks. A special value of 9 oktas is used when the is obscured by , , or other meteorological phenomena, making cloud cover impossible to assess. Qualitative terminology provides a descriptive for cloud amounts in reports and forecasts. For example, of 3 to 4 oktas is commonly termed "scattered," implying isolated cloud patches with significant clear areas remaining, while 5 to 7 oktas is described as "broken," featuring larger cloud formations with intermittent breaks in coverage. In aviation contexts, such as (Meteorological Aerodrome Report) observations, standardized abbreviations convey these amounts efficiently: SKC for sky clear (0 oktas), FEW for few clouds (1–2 oktas), SCT for scattered (3–4 oktas), BKN for broken (5–7 oktas), and for overcast (8 oktas). These terms and codes facilitate quick interpretation for pilots and meteorologists, emphasizing practical and flight implications. The okta scale offers a structured visual assessment of cloud coverage, as outlined below:
OktasCoverage FractionDescription
00/8Sky completely clear (fine).
1≤1/8 (not zero)Minimal cloud, fine.
22/8Sparse cloud, fine.
33/8Partial (partly cloudy).
44/8Half the sky covered ().
55/8Predominantly cloudy.
66/8Mostly cloudy.
7≥7/8 (not 8/8)Heavily clouded (cloudy).
88/8Fully , no breaks.
9ObscuredSky hidden by or ; cloud amount indeterminable.
These levels are determined by estimating the proportion of the sky dome obscured by clouds of any type or height, prioritizing the total coverage rather than individual cloud layers.

Observation Methods

Observation of cloud cover in oktas primarily relies on visual estimation by trained meteorologists at ground-based weather stations. The observer positions themselves in an open area with an unobstructed view of the sky, standing with their back to the sun or light source to reduce glare and enhance visibility of cloud edges. The sky is mentally divided into eight equal sectors, each representing one okta, and the total coverage is estimated as the number of sectors obscured by clouds from all layers combined; for uneven distributions, the sky may be quartered, with estimates from each quadrant summed and adjusted to fit the 0-8 okta scale. Multiple views are often averaged over a short period, typically several minutes, to account for transient changes and achieve the recommended uncertainty of no more than 2/8 okta. To improve precision in visual assessments, auxiliary tools such as the cloud mirror are employed. This device consists of a flat mirror marked into eight or sixteen equal sections with a dark grid; placed on the ground, it reflects the overhead , allowing the observer to count the sections containing cloud reflections and directly derive the okta value by proportion. Similar aids, including hemispherical viewers or patch-based estimators that simulate divided domes, facilitate consistent quantification by standardizing the observer's and minimizing subjective bias. These tools are particularly useful in training or when direct overhead viewing is challenging due to or conditions. The (WMO) provides standardized guidelines to ensure consistency across global observations. Total cloud amount is defined as the proportion of the celestial dome covered by any opaque or translucent clouds, irrespective of layering or type, with overlapping coverages summed but not exceeding 8 oktas; if lower layers are fully obscured by higher ones, only the total is reported unless layers are distinguishable. In cases of obscured sky due to precipitation like , , or , the cover is coded as 9 oktas, and vertical is measured separately using instruments like transmissometers rather than attempting okta estimation. Observations must resolve to 1/8 okta increments, with a required accuracy of 1/8 okta, emphasizing representative sampling over the station's vicinity rather than a single point. Contemporary automated methods supplement manual observations through satellite imagery analysis. Geostationary satellites like Japan's Himawari-8 and the U.S. GOES series capture high-resolution visible and infrared images, from which cloud detection algorithms—such as threshold-based masking combined with numerical weather prediction inputs—derive cloud masks and cover estimates across large areas. These estimates enable real-time, wide-scale monitoring that complements station data but may underrepresent low-level or thin clouds. For instance, Himawari-8's Advanced Himawari Imager processes data at 10-minute intervals to produce cloud products on a 0.02° grid, supporting cloud cover assessments over the Asia-Pacific region.

History and Standardization

Origins of the Okta System

The term okta originates from the Greek word , meaning "eight," denoting the division of the dome into eight equal parts to quantify coverage. This etymological root underscores the system's design for precise, fractional assessment of sky obstruction by clouds, where one okta represents one-eighth coverage. In the early 19th century, foundational work in classification by English meteorologist Luke Howard advanced systematic meteorological observation, proposing a for cloud types in 1802 that emphasized empirical description over vague terminology. Howard's efforts, presented to the Askesian Society, shifted cloud study from anecdotal accounts to structured categorization, setting the stage for later quantitative extensions like the okta, though his system primarily addressed morphology rather than extent. By the early 20th century, the British Meteorological Office formalized the okta system around 1914, replacing prior qualitative descriptors—such as "" (b), "cloudy" (c), or "" (o) derived from adapted Beaufort notations—with numerical eighths for total amount in synoptic charts. This transition, effective from January 1, 1914, enabled more objective data compilation for mapping, evolving from subjective terms like "cloudy" to scalable values (0 for clear to 8 for fully ) that supported international comparability in . The okta's development reflected broader meteorological standardization, influenced by precedents like the for wind force, introduced in 1805, which similarly promoted numerical evaluation of variable phenomena to enhance observational consistency across reports.

Adoption by Meteorological Organizations

The (WMO) formalized the adoption of the okta system for measurement through its International Codes for the representation of meteorological information, particularly in the (surface synoptic observations) format, where section 6 specifies total cloud amount in oktas (0 to 8, with 9 for sky obscured). This standardization built on earlier international efforts by the International Meteorological Organization (IMO), with the shift to oktas from tenths occurring in January 1949 for global reporting practices, enabling consistent data exchange across meteorological services. National meteorological organizations implemented the okta system in alignment with WMO guidelines during the mid-20th century. In the United States, the (NWS) incorporated oktas into surface weather observations as per the Federal Meteorological Handbook No. 1, which defines sky cover in eighths attributable to clouds or obscurations, reflecting the 1949 international transition and subsequent WMO standards. European national services adopted the system through collaborative frameworks like EUMETNET, established in 1990 to coordinate WMO-compliant operations, ensuring uniform okta-based reporting for regional data sharing and forecasting. Similarly, the (ICAO) included oktas in Annex 3 (Meteorological Service for ), mandating cloud amount reporting in eighths for , with accuracy requirements of ±1 okta for observations at aerodromes. The okta system's evolution within WMO regulations has addressed integration with and observational challenges. The 1995 edition of the Manual on Codes (WMO-No. 306) updated alphanumeric formats to incorporate satellite-derived meteorological data, facilitating the blending of ground-based okta observations with space-based estimates for improved global coverage. WMO resolutions and guidelines, such as those in the Manual on the Observation of Clouds and Other Meteors (WMO-No. 407), have clarified ambiguities in multi-layer cloud reporting; total represents the fraction of the celestial dome obscured by any visible cloud (union of layers), not a simple sum of individual layer amounts, which may exceed 8 oktas if overlapping—observers estimate by assessing superposition over time as clouds move.

Representation and Notation

Symbolic Codes in Weather Reports

In weather reports, cloud cover measured in oktas is communicated through standardized textual and diagrammatic codes to ensure consistency across global meteorological networks. The (WMO) defines these codes in formats such as for surface synoptic observations and for aviation weather reports, allowing observers to encode total sky coverage precisely without ambiguity. In the SYNOP code (FM-12), total cloud cover is reported in Section 1 using the single digit N immediately following visibility data, where N=0 denotes clear sky (0 oktas), N=1 for 1 okta or less but not zero, N=2 for 2-3 oktas, N=3 for 3 oktas, N=4 for 4 oktas, N=5 for 5 oktas, N=6 for 6 oktas, N=7 for 7 oktas, N=8 for 8 oktas (overcast), and N=9 signifies the sky is totally obscured or more than 9/10 covered due to fog, precipitation, or other phenomena preventing observation. This coding follows WMO Code Table 2700, which equates each okta to one-eighth of the celestial dome covered by clouds or obscurations. For layered clouds, additional groups in Sections 3 and 8 provide details on amounts and types: Section 3 uses 6NhCLCMCH, where Nh codes the amount of low-level clouds (using similar ranges as Table 2700 or / for none) if present, or middle-level if no low clouds, followed by CL, CM, and CH codes for low, medium, and high cloud types respectively from WMO specification tables; Section 8 extends this with 8NCLh for low cloud amount and type at specific heights. METAR reports, used primarily in , employ qualitative descriptors tied to okta ranges rather than numeric values for brevity in transmission. These include SKC or CLR for sky clear (0 oktas), FEW for few clouds (1-2 oktas), SCT for scattered (3-4 oktas), BKN for broken (5-7 oktas), for (8 oktas), and for vertical visibility when the sky is obscured. Each descriptor is followed by a three-digit in hundreds of feet above ground level, such as FEW010 indicating 1-2 oktas at 1,000 feet; multiple layers can be reported in order of increasing . Diagrammatic symbols in traditional models visually represent okta values through modifications to a central circle, facilitating quick interpretation on synoptic charts. The circle remains empty for 0 oktas (clear), partially filled or shaded in increments for 1-7 oktas (e.g., one-eighth shaded for 1 okta, half-filled for 4 oktas), and fully black for 8 oktas (); in some conventions, diagonal slashes substitute shading, with one slash for 1-2 oktas, two for 3-4, three for 5-6, and a filled circle for 7-8. Distinctions for levels are noted separately: low (), medium (), and high () types are symbolized with specific icons (e.g., cumulus for , altostratus for , for ) placed below or above the central circle, often with their own amount indicators if significant. While oktas are the WMO standard, some national services like the U.S. record observations in tenths and convert for reporting, influencing symbol designs. These symbolic codes originated in the early with manual observation practices and were formalized in the through international agreements by the International Meteorological Committee, evolving into the format by the 1940s under WMO precursors. By the late , they transitioned to digital systems like BUFR (Binary Universal Form for the Representation of meteorological data), introduced in the for automated global exchange, where cloud amount is encoded via descriptor 0 20 011 using values 0-8 for oktas and 9 for obscured, enabling machine-readable transmission without loss of precision.

Historical Hand-Drawn Maps

In the early , particularly from the to the , synoptic charts relied on hand-drawn symbols to represent in oktas at stations, plotted within standardized station circles. These techniques, employed by organizations such as the UK Meteorological Office and the U.S. Weather Bureau, used simple straight-line notations inside the circles to denote cloud amounts from 0 to 8 oktas, allowing meteorologists to quickly visualize on large-scale maps during manual plotting sessions. For instance, an empty circle indicated 0 oktas (clear sky), while one diagonal line represented 1-2 oktas, progressing to two lines for 3-4 oktas, three lines for 5-6 oktas, and multiple intersecting lines or a crosshatch pattern for 7-8 oktas (). The design of these symbols was constrained by the limitations of early data transmission systems, notably the 5-bit Baudot-Murray codes used for international reports via telegraph and circuits from the onward. This 5-unit code, with only 32 possible characters, required to be encoded numerically (0-8) in alphanumeric messages, which plotters then translated into graphical lines upon receipt, limiting representations to simplified forms like 0-4 lines to approximate the full efficiently under time pressure. Historical archives provide concrete examples of these practices, such as the U.S. Weather Bureau's hand-drawn synoptic maps from , which depict North American weather patterns with line-based symbols (in tenths, converted to oktas for codes) in station circles, as seen in digitized collections of daily surface analyses. Following , the transition to mechanized printing presses and improved facsimile transmission reduced reliance on fully hand-drawn charts, enabling more uniform reproduction of symbols while retaining the core okta notation.

Modern Digital and Unicode Symbols

In contemporary meteorological applications, okta values are digitally represented using (SVG) and (GIS) tools to overlay data on interactive maps. For instance, GIS platforms like enable the visualization of total in oktas through layered symbology, where numeric values or graduated symbols indicate the fraction of sky obscured, facilitating analysis in and . Similarly, web-based weather services employ SVG standards to render customizable icons depicting okta levels, ensuring consistent scaling across devices in applications that integrate . Unicode provides approximations for okta symbols through geometric shapes in the block, though no dedicated code points exist for exact 1-7 okta values, leading to creative mappings for partial coverage. Common examples include U+25EF (◯, white circle) for 0 oktas denoting clear , and U+25CF (●, ) for 8 oktas indicating full overcast. These approximations allow text-based or lightweight digital interfaces to convey cloud amount without custom graphics, but the lack of precise symbols for intermediate oktas often requires supplementary numeric labels. Rendering challenges arise from inconsistent font and operating system support for these Unicode characters, where symbols may appear distorted, missing, or substituted in older systems or non-standard fonts, potentially affecting data readability in global applications. The (WMO) recommends fallback methods, such as or plain numeric notation (e.g., "4/8" for half cover), to ensure accessibility in text-only environments or legacy software.

Applications and Limitations

Use in Aviation and Forecasting

In aviation meteorology, the okta scale is integral to METAR (Meteorological Aerodrome Reports) and TAF (Terminal Aerodrome Forecasts), where cloud cover is denoted using abbreviations that correspond to specific okta ranges to inform pilots about ceiling and visibility conditions. For instance, "BKN020" indicates broken clouds—covering 5 to 7 oktas—at an altitude of 2,000 feet above ground level, signaling potential restrictions on visual flight. These reports are essential for determining compliance with (VFR), which require pilots to maintain clear-of-clouds separation (typically 500 feet below, 1,000 feet above, and 2,000 feet horizontally from clouds) and minimum visibility of 3 statute miles during the day, or (IFR) when cloud cover exceeds these thresholds, necessitating instrument navigation. High okta values, such as overcast (8 oktas, denoted as "OVC"), often trigger IFR operations or ground delays to ensure safety amid reduced visibility. Oktas play a key role in by integrating into models, such as those from the European Centre for Medium-Range Weather Forecasts (ECMWF), where total is simulated and output in percentages convertible to oktas (e.g., 75% equates to 6 oktas) to predict cloud evolution and layering over time. This data supports the issuance of alerts, particularly when high okta coverage (e.g., 7-8 oktas) coincides with thunderstorms, indicating potential for hazardous conditions like , , or that could impact . In such forecasts, okta-based cloud assessments help prioritize warnings in aviation SIGMETs (Significant Meteorological Information), enabling route adjustments or diversions. A notable application occurred during the 2010 volcanic eruption in , where okta-derived observations from ground stations and satellite data aided in tracking the ash plume's dispersion, which mimicked dense layers and led to widespread closures affecting over 100,000 flights. Meteorological reports incorporating high okta values for the ash-obscured skies provided critical context for Advisory Centers (VAACs) to model plume extent and height, informing real-time decisions on flight safety and resumption. This event underscored oktas' utility in non-traditional scenarios, enhancing resilience to atmospheric hazards.

Comparisons to Other Cloud Cover Measures

The okta system, which quantifies cloud cover in eighths of the sky dome from 0 to 8, contrasts with the tenths employed in historical U.S. weather observations (pre-1996), where coverage was reported in increments of one-tenth (0 to 10). In the United States, prior to the mid-20th century, sky conditions were often categorized broadly using tenths, such as clear (0 tenths), scattered (1–5 tenths), broken (6–9 tenths), and (10 tenths), before the 1996 transition to the okta (eighths) in and synoptic observations for greater international consistency. This tenths approach allows for finer granularity, enabling distinctions like 4/10 coverage that might equate to the ambiguous 3–4 oktas range in the okta system, which is particularly useful in contexts requiring decimal precision. However, neither accounts for type or height, focusing solely on total areal coverage. In satellite-based , is frequently estimated as a continuous (0–100%), derived from data, which offers high-resolution spatial mapping but requires conversion for compatibility with ground-based systems like oktas. To align with oktas, values are divided by 12.5% (since 100% ÷ 8 = 12.5%), yielding an approximate okta equivalent; for instance, 50% coverage corresponds to roughly 4 oktas. Qualitative scales, such as "clear," "" (typically 3–5 oktas or 30–60%), or "," are also used in satellite-derived forecasts and reports for simplified communication, though they lack the quantitative rigor of either oktas or tenths. The okta system's primary advantage lies in its simplicity for manual human observations, as the sky can be mentally divided into eight equal parts using directions and , facilitating quick estimates in conditions without specialized tools. In contrast, the tenths scale demands higher precision, which can introduce observer variability and is better suited to automated or applications, though it complicates data harmonization. Oktas benefit from global standardization by the , enabling consistent cross-border comparisons, whereas tenths remain regionally prominent in historical U.S. datasets, often necessitating conversions that may introduce minor errors.

References

  1. [1]
    The Leader in Identity Management - Okta
    We're the leading independent partner for Identity management. Our vision is to free everyone to safely use any technology.Careers · Leadership · Contact Us
  2. [2]
    okta-20250131 - SEC.gov
    As of January 31, 2025, we had more than 19,650 customers, including more than 4,800 customers with an annual contract value greater than $100,000. Our ...
  3. [3]
    Customer Success Stories - Okta
    Top brands trust Okta. Two thirds of the Fortune 100 and thousands of other organizations count on Okta for their Identity-powered journeys.
  4. [4]
    It's Official: Okta Joins Forces With Auth0
    May 3, 2021 · We've successfully completed the acquisition. I've long admired the impressive platform and developer community Auth0 co-founders Eugenio Pace ...Missing: acquires | Show results with:acquires
  5. [5]
    EX-99.1 - SEC.gov
    Mar 3, 2021 · Okta will acquire Auth0 for approximately $6.5 billion in Okta Class A common stock (subject to customary purchase price adjustments and ...<|control11|><|separator|>
  6. [6]
    OKTA) to The Nasdaq Stock Market - Yahoo Finance
    Apr 7, 2017 · Nasdaq Welcomes Okta, Inc. (Nasdaq: OKTA) to The Nasdaq Stock Market. GlobeNewswire. April 7, 2017.<|control11|><|separator|>
  7. [7]
    How we measure cloud - Met Office
    1 okta represents a cloud amount of 1 eighth or less, but not zero; 7 oktas represents a cloud amount of 7 eighths or more, but not full cloud cover; 8 oktas ...
  8. [8]
    [PDF] Synoptic Code Symbols with Range of Values
    Okta. Used for the measurement of total cloud cover. One okta of cloud cover is the equivalent of 1/8 of the sky covered with cloud. Period. See wave period ...
  9. [9]
    Defintion of Oktas
    0. Sky clear. Fine ; 1. 1/8 of sky covered or less, but not zero. Fine ; 2. 2/8 of sky covered. Fine ; 3. 3/8 of sky covered. Partly Cloudy ; 4. 4/8 of sky covered.
  10. [10]
    WMO CODE TABLE 2700
    2700 ; 9, Sky obscured by fog and/or other meteorological phenomena ; /, Cloud cover is indiscernible for reasons other than fog or other meteorological phenomena ...
  11. [11]
    [PDF] JO 7900.5D - Surface Weather Observing
    Dec 20, 2016 · SCATTERED (SCT) represents sky cover of 3/8ths to 4/8ths at and below the level of a layer aloft. e. BROKEN (BKN) represents sky cover of 5 ...<|control11|><|separator|>
  12. [12]
    Abbreviations - Met Office
    Becoming. BKN. Broken (5 to 7 oktas). BL. Blowing. BLW. Below. BR. Mist. BTN ... FC. Funnel cloud. FCST. Forecast. FEB. February. FEW. Few (1 or 2 oktas). FG. Fog.
  13. [13]
    [PDF] Local Climatological Data Version 2 (LCDv2) Dataset Documentation
    1) ccc is Coverage: CLR (clear sky), FEW (few clouds), SCT (scattered clouds), BKN (broken clouds), OVC ... 1-2 oktas/1-3 tenths is defined as FEW (few clouds).Missing: terminology | Show results with:terminology
  14. [14]
    [PDF] Guide to Meteorological Instruments and Methods of Observation
    One of the purposes of the World Meteorological. Organization (WMO) is to coordinate the activities of its 188 Members in the generation of data and.
  15. [15]
    [PDF] S52-2/214-1992 - Publications du gouvernement du Canada
    ... cloud mirror. SEE mirror nephoscope cloud model. The current approach of nnodellers is to make up some cloud model based on simple physical arguments, include ...
  16. [16]
    [PDF] High-resolution Cloud Analysis Information derived from Himawari-8 ...
    HCAI includes cloud mask, snow ice mask, cloud type, cloud top height, and quality control, with 0.02° spatial resolution, derived from Himawari-8 data.
  17. [17]
    OKTA definition in American English - Collins Dictionary
    A unit used in meteorology to measure cloud cover, equivalent to a cloud cover of one eighth of the sky ... Word origin. C20: from Greek okta-, oktō eight.
  18. [18]
    OKTA Definition & Meaning | Dictionary.com
    Okta definition: a unit used in meteorology to measure cloud cover, equivalent to a cloud cover of one eighth of the sky ... Word History and Origins. Origin ...Missing: etymology | Show results with:etymology<|control11|><|separator|>
  19. [19]
    Our Cloud Names Come From a 1700s Amateur Meteorologist
    Nov 28, 2017 · Our Cloud Names Come From a 1700s Amateur Meteorologist. Luke Howard's nomenclature inspired writers as well as scientists. Kat Eschner.
  20. [20]
    The Useful Pursuit of Shadows | American Scientist
    Clouds were first described systematically by Luke Howard, a London pharmacist and amateur meteorologist, in an 1802 address to the Askesian Society. Howard's ...
  21. [21]
    [PDF] Weather charts - Met Office
    Sky clear (0 oktas). 6 oktas covered. 1 okta or less of sky covered, but not zero. 7 oktas covered. 2 oktas of sky covered. 8 oktas covered. 3 oktas of sky ...
  22. [22]
    The Beaufort Wind Scale | Royal Meteorological Society
    The Beaufort Scale is an empirical measure relating wind speed to observed conditions, created to standardize subjective weather observations.
  23. [23]
    On Trends and Possible Artifacts in Global Ocean Cloud Cover ...
    The earlier change, in 1949, changed reporting of cloud cover in logbooks from tenths to oktas (Elms et al. 1993). Confusion related to this change appears to ...Missing: British | Show results with:British
  24. [24]
    [PDF] MANUAL ON THE OBSERVATION OF CLOUDS AND OTHER ...
    This manual covers the definition of meteors, their classification, and the definition of clouds, including their appearance, classification, and ...Missing: okta SYNOP
  25. [25]
    [PDF] SYNOP Data Format (FM-12) - Priyom.org
    1 -- manned station -- weather group included. 2 -- manned station -- omitted, no significant weather. 3 -- manned station -- omitted, no weather ...
  26. [26]
    JetStream Max: Surface Weather Plot Symbols - NOAA
    Feb 10, 2025 · Sky Cover Symbols. These are the ten symbols that represent the total amount of sky cover at the time of the observation (reported in eigths).
  27. [27]
    Station Model Information for Weather Observations
    May 12, 2022 · A weather symbol is plotted if at the time of observation, there is either precipitation occurring or a condition causing reduced visibility.
  28. [28]
    49-2/_CloudAmountReportedAtAerodrome - WMO Codes Registry :
    Oct 24, 2019 · This code table contains a subset of the cloud amount categories defined in Part B FM 94 BUFR Code Table 0 20 008.
  29. [29]
    Remarkable Surface Synoptic Maps from the 1930s - AMS Journals
    Illustrated example from the 1930s of an unmined data source for research into mesoscale synoptic weather phenomena. professor at The Ohio State University, ...Missing: charts | Show results with:charts
  30. [30]
    https://geo.libretexts.org/Bookshelves/Meteorology_and_Climate_Science/Practical_Meteorology_%28Stull%29/06%253A_Clouds/6.05%253A_Sky_Cover_%28Cloud_Amount%29
  31. [31]
    wmdr/unit/okta - WMO Codes Registry
    Oct 14, 2019 · URI: http://codes.wmo.int/wmdr/unit/okta. Unit of cloud amount, expressed as number of eighths of the sky dome that is covered by clouds; ...
  32. [32]
    Trends in U.S. Total Cloud Cover from a Homogeneity-Adjusted ...
    Before this date, sky condition was reported as one of four broad categories defined in terms of tenths of sky cover: clear (0), scattered (1–5), broken (6–9), ...
  33. [33]
    [PDF] Column Water Vapor Content in Clear and Cloudy Skies
    Nor does the fact that U.S. synoptic observations are made in tenths, which must have been converted to okta values. Only if both radiosonde and sky-cover data ...
  34. [34]
    6.5: Sky Cover (Cloud Amount) - Geosciences LibreTexts
    Dec 9, 2022 · It is measured in eights (oktas) according to the World Meteorological Organization. Table 6-7 gives the definitions for different cloud amounts ...
  35. [35]
    Impact of Moderate Resolution Imaging Spectroradiometer (MODIS ...
    Aug 12, 2015 · Okta values are converted into percentages by multiplying them by 12.5%. In order to be able to make a comparison with MODIS data, we used ...<|separator|>
  36. [36]
    Is there any difference between 'partly cloudy' and 'partly sunny'?
    Jan 8, 2024 · Partly cloudy is the same as partly sunny, with 3 to 5 oktas of opaque cloud cover. Of course, partly sunny cannot be used in reporting nighttime conditions.
  37. [37]
    Ground‐based observations of clouds through both an automatic ...
    Dec 7, 2015 · Table 1 depicts the code figures for cloud cover in accordance with the recommendations by WMO. Thus, code figure 1 is for cloud cover ≤ 1 okta ...Introduction · Site and instruments · Methodology · Results and discussion