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The path of jet streams affects cyclonic storm systems at lower levels in the atmosphere, and so knowledge of their course has become an important part of weather forecasting. For example, in 2007 and 2012, Britain experienced severe flooding as a result of the polar jet staying south for the summer.
This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion); the top of the stratosphere has a temperature of about 270 K (−3°C or 26.6°F). [9] [page needed]
T is the absolute temperature in kelvins = 288.15 K at sea level, g is the acceleration due to gravity = 9.806 65 m/s 2 at sea level, P is the pressure at a given point at elevation z in Pascals, and; P 0 is pressure at the reference point = 101,325 Pa at sea level.
Thus the standard consists of a tabulation of values at various altitudes, plus some formulas by which those values were derived. To accommodate the lowest points on Earth, the model starts at a base geopotential altitude of 610 meters (2,000 ft) below sea level, with standard temperature set at 19 °C.
The NASA Earth Global Reference Atmospheric Model (Earth-GRAM) was developed by the Marshall Space Flight Center to provide a design reference atmosphere that, unlike the standard atmospheres, allows for geographical variability, a wide range of altitudes (surface to orbital altitudes), and different months and times of day. It can also ...
The reduction in velocity near the surface is a function of surface roughness, so wind velocity profiles are quite different for different terrain types. [5] Rough, irregular ground, and man-made obstructions on the ground can reduce the geostrophic wind speed by 40% to 50%. [9] [10] Over open water or ice, the reduction may be only 20% to 30%.
The amount of water that can exist as vapor in a given volume increases with the temperature. When the amount of water vapor is in equilibrium above a flat surface of water the level of vapor pressure is called saturation and the relative humidity is 100%. At this equilibrium there are equal numbers of molecules evaporating from the water as ...
It is the coldest place on Earth and has an average temperature around −85 °C (−120 °F; 190 K). [22] [23] Just below the mesopause, the air is so cold that even the very scarce water vapor at this altitude can condense into polar-mesospheric noctilucent clouds of ice particles. These are the highest clouds in the atmosphere and may be ...