In aviation, ceiling is a measurement of the height of the base of the lowest clouds (not to be confused with cloud base which has a specific definition) that cover more than half of the sky (more than 4 oktas) relative to the ground. Ceiling is not specifically reported as part of the METAR (METeorological Aviation Report) used for flight planning by pilots worldwide, but can be deduced from the lowest height with broken (BKN) or overcast (OVC) reported. [1] A ceiling listed as "unlimited" means either that the sky is mostly free of cloud cover, or that the cloud is high enough not to impede Visual Flight Rules (VFR) operation.
In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).
In aviation, visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minima, i.e., in visual meteorological conditions (VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate the aircraft with visual reference to the ground, and by visually avoiding obstructions and other aircraft.
Diamond dust is a ground-level cloud composed of tiny ice crystals. This meteorological phenomenon is also referred to simply as ice crystals and is reported in the METAR code as IC. Diamond dust generally forms under otherwise clear or nearly clear skies, so it is sometimes referred to as clear-sky precipitation. Diamond dust is most commonly observed in Antarctica and the Arctic, but can occur anywhere with a temperature well below freezing. In the polar regions of Earth, diamond dust may persist for several days without interruption.
The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space.
A cloud base is the lowest altitude of the visible portion of a cloud. It is traditionally expressed either in metres or feet above mean sea level or above a planetary surface, or as the pressure level corresponding to this altitude in hectopascals.
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 the advancement of technology in civil aviation, the METAR is sent as IWXXM model.
In meteorology and aviation, terminal aerodrome forecast (TAF) is a format for reporting weather forecast information, particularly as it relates to aviation. TAFs are issued at least four times a day, every six hours, for major civil airfields: 0000, 0600, 1200 and 1800 UTC, and generally apply to a 24- or 30-hour period, and an area within approximately five statute miles (8.0 km) from the center of an airport runway complex. TAFs are issued every three hours for military airfields and some civil airfields and cover a period ranging from 3 hours to 30 hours.
A pilot report or PIREP is a report of actual flight or ground conditions encountered by an aircraft. Reports commonly include information about atmospheric conditions or airport conditions. This information is usually relayed by radio to the nearest ground station, but other options also exist in some regions. The message would then be encoded and relayed to other weather offices and air traffic service units.
VFR over-the-top (OTT) refers to flying over top of clouds in visual flight, rather than with reference to instruments. This is usually done for brief amount of time to avoid weather or turbulence.
Overcast or overcast weather, as defined by the World Meteorological Organization, is the meteorological condition of clouds obscuring at least 95% of the sky. However, the total cloud cover must not be entirely due to obscuring phenomena near the surface, such as fog.
Colour states is a system used for quickly showing meteorological conditions.
In meteorology, an okta is a unit of measurement used to describe the amount of cloud cover at any given location such as a weather station. Sky conditions are estimated in terms of how many eighths of the sky are covered in cloud, ranging from 0 oktas through to 8 oktas. In addition, in the SYNOP code there is an extra cloud cover indicator '9' indicating that the sky is totally obscured, usually due to dense fog or heavy snow.
In meteorology, station models are symbolic illustrations showing the weather occurring at a given reporting station. Meteorologists created the station model to fit a number of weather elements into a small space on weather maps. This allows map users to analyze patterns in atmospheric pressure, temperature, wind speed and direction, cloud cover, precipitation, and other parameters. The most common station plots depict surface weather observations although upper air plots at various mandatory levels are also frequently depicted.
Airport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing in the United States and Canada and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings.
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.
American Airlines Flight 723 was a scheduled American Airlines flight from Boston Airport in Massachusetts, to Chicago Midway Airport in Illinois. On September 16, 1953, a Convair 240 propliner flying this route crashed while attempting to land at Albany Airport in upstate New York, killing all 28 people on board.
AeroUnion Flight 302, operated by an Airbus A300B4-203F cargo aircraft, crashed in poor weather on final approach at General Mariano Escobedo International Airport, Monterrey, Mexico around 23:18 CDT on 13 April 2010, after a flight from Mexico City. All five people on board were killed, as well as one on the ground.
Swiss International Air Lines Flight 850 was an international scheduled passenger flight from Basel, Switzerland, to Hamburg, Germany. On 10 July 2002, the flight was unable to land at Fuhlsbüttel Airport due to weather. Attempts were made to divert to other airports at Berlin and Eberswalde before the crew decided to land at Werneuchen. On landing, the aircraft struck an earth bank which ripped off all three undercarriage legs, and came to rest on its belly with an engine on fire. One of the sixteen passengers suffered minor injuries. The aircraft was written off.
Altimeter setting is the value of the atmospheric pressure used to adjust the scale of a pressure altimeter so that it indicates the height of an aircraft above a known reference surface. This reference can be the mean sea level pressure (QNH), the pressure at a nearby surface airport (QFE), or the "standard pressure level" of 1,013.25 hectopascals which gives pressure altitude and is used to maintain one of the standard flight levels.
This glossary of meteorology is a list of terms and concepts relevant to meteorology and atmospheric science, their sub-disciplines, and related fields.