Temperature
Patterns
Inversions
Under normal circumstances, air temperature tends to
decrease with increasing elevation above the surface
through the troposphere. Under particular conditions the
lapse rate of temperature is reversed
and temperatures increase with increasing elevation
creating an inversion or inverted
lapse rate of temperature.
Figure 5.9 Radiation inversion
A radiation inversion
commonly occurs when the evening air is still and there
are no clouds to trap heat. Surface temperature drops as
longwave radiation emitted by the Earth escapes to
space. Air in contact with the surface cools, but that at
a higher elevation and not in direct contact with the
earth remains somewhat warmer creating the inversion. Cool
air will collect in depressions as air density increases
and gravity pulls it down slope.
Figure 5.10 Sea breeze inversion
Sea breeze inversions
occur along windward coasts bordered by cold ocean
currents. The bottom layer of a warm maritime air mass
originating over the ocean becomes cooler upon coming in
contact with the cooler water bordering the coast. This
creates cooler air near the surface with warmer air aloft.
Figure
5.11 Subsidence inversion
Areas
dominated by high pressure are also subject to inversions.
Subsidence inversions form when subsiding
air undergoes adiabatic heating aloft, while air in
contact with the surface remains cooler.
Subsidence and subsidence inversions in association with
high pressure are discussed in Chapter 6.
Previous
| Continue
|