Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automated weather stations , or in a hybrid scheme using weather observers to augment the otherwise automated weather station. The ICAO defines the International Standard Atmosphere (ISA), which is the model of the standard variation of pressure , temperature , density , and viscosity with altitude in the Earth's atmosphere , and is used to reduce a station pressure to sea level pressure. Airport observations can be transmitted worldwide through the use of the METAR observing code. Personal weather stations taking automated observations can transmit their data to the United States mesonet through the Citizen Weather Observer Program (CWOP), the UK Met Office through their Weather Observations Website (WOW), or internationally through the Weather Underground Internet site. A thirty-year average of a location's weather observations is traditionally used to determine the station's climate . In the US a network of Cooperative Observers make a daily record of summary weather and sometimes water level information.
31-1050: Automated Meteorological Data Acquisition System ( AMeDAS ), commonly known in Japanese as "アメダス" ( amedasu ), is a high-resolution surface observation network developed by the Japan Meteorological Agency (JMA) used for gathering regional weather data and verifying forecast performance. The system began operating on 1 November 1974, and currently comprises 1,300 stations throughout Japan (of which over 1,100 are unstaffed), with an average separation of 17 km (11 mi). Observations at staffed stations cover weather, wind direction and speed , types and amounts of precipitation , types and base heights of clouds, visibility , air temperature, humidity , sunshine duration , and atmospheric pressure . All of these (except weather, visibility and cloud-related meteorological elements) are observed automatically. At unstaffed stations, observations are performed every 10 minutes. About 700 of
62-581: A pilot report or PIREP, colour states and runway visual range (RVR). In addition, a short period forecast called a TREND may be added at the end of the METAR covering likely changes in weather conditions in the two hours following the observation. These are in the same format as a Terminal Aerodrome Forecast (TAF). The complement to METARs, reporting forecast weather rather than current weather, are TAFs. METARs and TAFs are used in VOLMET broadcasts. METAR code
93-528: A number of static variables that determine climate, including: latitude, altitude, proportion of land to water, and proximity to oceans and mountains. Degree of vegetation coverage affects solar heat absorption, water retention, and rainfall on a regional level. METAR METAR is a format for reporting weather information. A METAR weather report is predominantly used by aircraft pilots , and by meteorologists , who use aggregated METAR information to assist in weather forecasting . Today, according to
124-638: Is credited with taking the first systematic weather observations in Colonial America. He was a chaplain in the Swedes Fort colony near the mouth of the Delaware River. Holm recorded daily observations without instruments during 1644 and 1645. While numerous other accounts of weather events on the East Coast were documented during the 17th Century. President George Washington kept a detailed weather diary during
155-761: Is regulated by the World Meteorological Organization in consort with the International Civil Aviation Organization. In the United States, the code is given authority (with some U.S. national differences from the WMO/ICAO model) under the Federal Meteorological Handbook No. 1 (FMH-1), which paved the way for the U.S. Air Force Manual 15-111 on Surface Weather Observations, being the authoritative document for
186-485: Is still generally used to determine wind speed from manual observers out at sea. Ships with anemometers have issues with determining wind speeds at higher wind speeds due to blockage of the instruments by increasing high seas. Climate, (from Ancient Greek klima ) is commonly defined as the weather averaged over a long period of time. The standard averaging period is 30 years for an individual location, but other periods may be used. Climate includes statistics other than
217-432: Is the surface weather analysis , which plots isobars to depict areas of high pressure and low pressure . For over a century, reports from the world's oceans have been received real-time for safety reasons and to help with general weather forecasting. The reports are coded using the synoptic code , and relayed via radio or satellite to weather organizations worldwide. Buoy reports are automated, and maintained by
248-427: Is then delivered to the whole country after a quality check. As well as weather conditions, AMeDAS is also used in the observation of natural disasters . Temporary observation points are set up in areas where there are signs of volcanic eruptions or earthquakes. This meteorology –related article is a stub . You can help Misplaced Pages by expanding it . Surface observation Reverend John Campanius Holm
279-461: The weather occurring at a given reporting station . Meteorologists created the station model to plot a number of weather elements in a small space on weather maps . Maps filled with dense station-model plots can be difficult to read, but they allow meteorologists, pilots, and mariners to see important weather patterns. Weather maps are used to display information quickly showing the analysis of various meteorological quantities at various levels of
310-554: The International Standard Atmosphere (also known as ICAO Standard Atmosphere ), which is the model of the standard variation of pressure , temperature , density , and viscosity with elevation / altitude in the Earth's atmosphere . This is useful in calibrating instruments and designing aircraft, and is used to reduce a station's pressure to sea level pressure (SLP) where it can then be used on weather maps . In
341-728: The U.S. Armed Forces. A very similar code form to the METAR is the SPECI. Both codes are defined at the technical regulation level in WMO Technical Regulation No. 49, Vol II, which is copied over to the WMO Manual No. 306 and to ICAO Annex III. Although the general format of METARs is a global standard, the specific fields used within that format vary somewhat between general international usage and usage within North America. Note that there may be minor differences between countries using
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#1732886847559372-650: The United States Federal Aviation Administration (FAA) describes the report as aviation routine weather report , while the international authority for the code form, the World Meteorological Organization (WMO), describes it as the aerodrome routine meteorological report. The National Oceanic and Atmospheric Administration (part of the United States Department of Commerce ) and the United Kingdom's Met Office both employ
403-525: The United States and can vary significantly. In Canada, RMK is followed by a description of the cloud layers and opacities, in eighths ( oktas ). For example, CU5 would indicate a cumulus layer with 5 ⁄ 8 opacity. Cloud coverage is reported by the number of ' oktas ' (eighths) of the sky that is occupied by cloud. This is reported as: METARs can be expressed concisely using so-called aviation flight categories , which indicates what classes of flight can operate at each airport by referring to
434-805: The United States, the FAA mandates the taking of weather observations at larger airports for safety reasons. To help facilitate the purchase of an automated airport weather station , such as ASOS, the FAA allows federal dollars to be used for the installation of certified weather stations at airports. The airport observations are then transmitted worldwide using the METAR observing code. METAR reports typically come from airports or permanent weather observation stations. Reports are generated once an hour; however, if conditions change significantly, they may be updated in special reports called SPECIs. Surface weather observations can include
465-596: The WMO (who write the code on behalf of ICAO) FM 15-XII code. Details are listed in the FAA's Aeronautical Information Manual (AIM), but the non-compliant elements are mostly based on the use of non-standard units of measurement. This METAR example is from Trenton-Mercer Airport near Trenton , New Jersey , and was taken on 5 December 2003 at 18:53 UTC. METAR KTTN 051853Z 04011KT 1/2SM VCTS SN FZFG BKN003 OVC010 M02/M02 A3006 RMK AO2 TSB40 SLP176 P0002 T10171017= Note that what follows are not part of standard observations outside of
496-558: The advancement of technology in civil aviation, the METAR is sent as IWXXM model. Raw METAR is the most common format in the world for the transmission of observational weather data. It is highly standardized through the International Civil Aviation Organization (ICAO), which allows it to be understood throughout most of the world. In its publication the Aeronautical Information Manual ,
527-416: The appropriate meteorological organizations either to diagnose real-time conditions, or be used within weather forecast models. Data collected by land locations coding in METAR are conveyed worldwide via phone lines or wireless technology. Within many nations' meteorological organizations, this data is then plotted onto a weather map using the station model . A station model is a symbolic illustration showing
558-450: The atmosphere, in this case the surface layer. Maps containing station models aid in the drawing of isotherms , which more readily identifies temperature gradients, and can help in the location of weather fronts . Two-dimensional streamlines based on wind speeds show areas of convergence and divergence in the wind field, which are helpful in determining the location of features within the wind pattern. A popular type of surface weather map
589-434: The average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) glossary definition is: The main difference between climate and everyday weather is best summarized by the popular phrase "Climate is what you expect, weather is what you get." Over historic time spans there are
620-401: The base METAR code as adopted by the WMO member countries. A typical METAR contains data for the temperature , dew point , wind direction and speed, precipitation , cloud cover and heights, visibility , and barometric pressure . A METAR may also contain information on precipitation amounts, lightning , and other information that would be of interest to pilots or meteorologists such as
651-487: The country that moored the buoy in that location. Larger moored buoys are used near shore, while smaller drifting buoys are used farther out at sea. Due to the importance of reports from the surface of the ocean, the voluntary observing ship program , known as VOS, was set up to train crews how to take weather observations while at sea and also to calibrate weather sensors used aboard ships when they arrive in port, such as barometers and thermometers . The Beaufort scale
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#1732886847559682-1045: The definition used by the FAA. METAR is also known as Meteorological Terminal Aviation Routine Weather Report or Meteorological Aerodrome Report . METARs typically come from airports or permanent weather observation stations . Reports are generated once an hour or half-hour at most stations, but if conditions change significantly at a staffed location, a report known as a special ( SPECI ) may be issued. Some stations make regular reports more frequently, such as Pierce County Airport (ICAO code: KPLU) which issues reports three times per hour. Some METARs are encoded by automated airport weather stations located at airports, military bases, and other sites. Some locations still use augmented observations, which are recorded by digital sensors, encoded via software, and then reviewed by certified weather observers or forecasters prior to being transmitted. Observations may also be taken by trained observers or forecasters who manually observe and encode their observations prior to transmission. The METAR format
713-586: The following elements: METAR LBBG 041600Z 12003MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 9949//91= Personal weather stations, maintained by citizens rather than government officials, do not use METAR code. Software allows information to be transmitted to various sites, such as the Weather Underground globally, or the CWOP within the United States , which can then be used by
744-484: The ground. This example value equals 23.4 °C (74 °F) and 12.3 °C (54 °F). This example indicates a rising tendency of 0.6 millibars (0.018 inHg). This example shows 1.23 inches (31 mm) of rain. This example shows 2.46 inches (62 mm) of rain. This example indicates 60 minutes of sunshine. This example indicates 22.2 inches (560 mm) of snowfall. This example indicates 2.1 inches (53 mm) SWE. The following codes identify
775-606: The international codes as there are between those using the North American conventions. The two examples which follow illustrate the primary differences between the two METAR variations. The following is an example METAR from Burgas Airport in Burgas , Bulgaria . It was taken on 4 February 2005 at 16:00 Coordinated Universal Time (UTC). METAR LBBG 041600Z 12012MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 8849//91= North American METARs deviate from
806-626: The late 1700s at Mount Vernon, Virginia. The number of routine weather observers increased significantly during the 1800s. In 1807, Dr. B. S. Barton of the University of Pennsylvania requested members throughout the Union of the Linnaean Society of Philadelphia to maintain instrumented weather observing sites to establish a climatological history.During the early 1900s, numerous observer stations moved from farms to residential districts of towns, where service
837-622: The top of the last hour." Combinations of two precipitation types are accepted; e.g. , RASN ( Rain and snow mixed ), SHGSSN etc . TS, SH, FG, DS, SS, VA, PO, FC, BLSN, BLDU, BLSA TS, RA, FZRA, SN, BLSN, GR, GS, PL ( e.g.: METAR ... Q1010 RERA= ) The following METAR abbreviations are used in the United States; some are used worldwide: METAR and TAF Abbreviations and Acronyms: Additional METAR numeric codes listed after RMK. This example value equals −23.4 °C (−10 °F). This example value equals 12.3 °C (54 °F). This example value equals 12 inches of snow currently on
868-538: The unstaffed stations observe precipitation, air temperature, wind direction and speed, and sunshine duration, while the other stations observe only precipitation. For about 280 stations (staffed or unstaffed) located in areas of heavy snowfall, snow depth is also observed. All the observational data is transmitted to the AMeDAS Center at JMA Headquarters in Tokyo on a real time basis via dedicated telephone lines. The data
899-429: The visibility and ceiling in each METAR. Four categories are used in the U.S.: METAR abbreviations used in the weather and events section. Remarks section will also include began and end times of the weather events. Codes before remarks will be listed as "-RA" for "light rain". Codes listed after remarks may be listed as "RAB15E25" for "Rain began at 15 minutes after the top of the last hour and ended at 25 minutes after
930-510: Was available to mail the observation forms. By 1926, more than 5000 observing locations were located throughout the U.S., West Indies, and the Caribbean.In 1939, the Bureau of Aeronautics in the U. S. Navy began to actively develop automated weather stations. Surface weather observations have traditionally been taken at airports due to safety concerns during takeoffs and landings. The ICAO defines
961-410: Was introduced internationally on 1 January 1968, and has been modified a number of times since. North American countries continued to use a Surface Aviation Observation (SAO) for current weather conditions until 1 June 1996, when this report was replaced with an approved variant of the METAR agreed upon in a 1989 Geneva agreement. The WMO's publication No. 782 "Aerodrome Reports and Forecasts" contains