What is an inversion?
A. The average condition of temperature change in the Troposphere is for there to be an overall decrease of temperature with increasing height: a positive lapse rate (see Q/A 2A.6). However, in the ‘real’ Troposphere, frequent reversals of this ‘normal’ lapse are observed, particularly in the lower layers – these zones of increasing temperature with height are inversions (i.e. the inverse of the average state), and are very important for both synoptic/mesoscale meteorology (e.g. fog/stratus formation/dispersal), and pollution dispersion studies, as they cap layers of markedly stable and potentially stagnant air masses. Examples of inversions include those due to anticyclonic subsidence; cooling land by night (nocturnal inversions); and sea-breeze inversions, where cooler sea air under-cuts warmer land air. Where the inversion is associated with an abrupt lowering of the moisture content (sharp fall of dew point), at the altitude of the temperature rise, then interesting radio-refractio
The term “temperature inversion” literally refers to a reversal of normal vertical temperature patterns seen in our lower atmosphere. Temperature inversions are relatively common in valley areas. In wintertime, a temperature inversion occurs when cold air close to the ground is trapped by a layer of warmer air. As the inversion continues, air to the ground becomes stagnant and pollution becomes trapped close Inversions also occur during the summer months, but are a product of even hotter upper air trapping warm air close to the ground. The result is the same: we are unable to rid ourselves of the everyday pollution that we create. Air pollution will continue to accumulate until the weather pattern changes.
