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A typical METAR contains data for the airport identifier, time of observation, wind direction and speed, visibility, current weather phenomena such as precipitation, cloud cover and heights, temperature, dew point, and barometric pressure. This information forms the body of the report, consisting a maximum of 11 groups of information.
If visibility or cloud height measurements fall on a boundary (e.g. 5000 m visibility or 1500 ft cloud height) the colour state assumes the higher value in this case WHT. [ citation needed ] If an airfield runway is unusable for reasons other than clouds or low visibility (e.g. ice or other obstructions) then the word BLACK is written in full ...
It is reported within surface weather observations and METAR code either in meters or statute miles, depending upon the country. Visibility affects all forms of traffic: roads, railways, sailing and aviation. The geometric range of vision is limited by the curvature of the Earth and depends on the eye level and the height of the object being ...
To take the prevailing visibility, controllers reference a number of visual reference points: usually buildings, hills, or other geographic features. The value obtained is usually reported on a METAR and recorded on the ATIS. In Canada, it is the maximum visibility value common to sectors comprising one-half or more of the horizon circle. [1]
VFR / VMC visibility requirements in the US. In aviation, visual meteorological conditions (VMC) is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft.
If relative humidity is high (i.e., there is a small difference between the temperature and the dew point), mist or fog is reported, depending on the exact visibility. Fog is reported when visibility is 1/2 mile or less; mist is reported for visibilities greater than 0.5 miles (0.80 km) but less than 7 miles (11 km).
Also actiniform. Describing a collection of low-lying, radially structured clouds with distinct shapes (resembling leaves or wheels in satellite imagery), and typically organized in extensive mesoscale fields over marine environments. They are closely related to and sometimes considered a variant of stratocumulus clouds. actinometer A scientific instrument used to measure the heating power of ...
A TTF is a professionally considered forecast for weather over a two-hour period, [1] and is based on an actual weather report, such as a METAR or SPECI and appended to the end of it. [1] A TTF is similar to or sometimes in addition to a TAF , a terminal aerodrome forecast, but during the TTF's validity period is considered superior to a TAF.