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Winds aloft, officially known as the winds and temperatures aloft forecast, (known as "FD" in the US and Canada, but becoming known as "FB", following the World Meteorological Organization [WMO] nomenclature), is a forecast of specific atmospheric conditions in terms of wind and temperature at certain altitudes, typically measured in feet (ft) above mean sea level (MSL).
An upper-level jet streak. DIV areas are regions of divergence aloft, which usually leads to surface convergence and cyclogenesis. Constant pressure charts normally contain plotted values of temperature, humidity, wind, and the vertical height above sea level of the pressure surface. [29] They have a variety of uses.
Low pressure also creates surface winds deriving from high pressure zones and vice versa. Various symbols are used not just for frontal zones and other surface boundaries on weather maps, but also to depict the present weather at various locations on the weather map. In addition, areas of precipitation help determine the frontal type and ...
Their motion induces upper-level wind divergence, lifting and cooling the air ahead (downstream) of the trough and helping to produce cloudy and rain conditions there. Unlike fronts, there is not a universal symbol for a trough on a surface weather analysis chart. The weather charts in some countries or regions mark troughs by a line.
The station model uses a wind barb to show both wind direction and speed. The wind barb shows the speed using "flags" on the end. Each half of a flag depicts 5 kn (9.3 km/h; 5.8 mph) Each full flag depicts 10 kn (19 km/h; 12 mph) Each pennant (filled triangle) depicts 50 kn (93 km/h; 58 mph) [4]
A surface weather analysis for the United States on October 21, 2006. By that time, Tropical Storm Paul was active (Paul later became a hurricane). Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations.
During frontogenesis, the temperature gradient tightens and as a result, the thermal wind becomes imbalanced. To maintain balance, the geostrophic wind aloft and below adjust, such that regions of divergence/convergence form. Mass continuity would require a vertical transport of air along the cold front where there is divergence (lowered ...
Surface wind direction and speed is also forecast on this type of chart. Wave prognostic charts show the expected sea state at some future time. [ 2 ] Low-level prognostic charts used by aviators show the forecast between the Earth's surface and 24,000 feet (7,300 m) above sea level over the next two days.