It was Tor Bergeron who for the first time used the term ‘frontogenesis’ for the creation of new fronts. Later on, the term was extended to include the process of regeneration of the old and decaying fronts.
Image Source: erh.noaa.gov/bgm/casestudy/2006/june2006/graphics/slide40.jpg
Thus, frontogenesis, a Latin derived word, means ‘creation of altogether new fronts’ or ‘the regeneration of decaying fronts already in existence.’ Frontolysis, on the contrary, means the destruction or dying of a front.
It would not be out of place to mention that fronts do not come into existence all of a sudden; rather they appear only after the processes of frontogenesis have been in operation for quite some time.
ADVERTISEMENTS:
In the same way, the act of weakening or vanishing of the existing fronts is not accomplished suddenly. The process of frontolysis must continue for some time in order to destroy an existing front.
Frontogenesis is likely to occur when the wind blows in such a way that the isotherms become packed along the leading edge of the intruding air mass. Convergence of the wind toward a point or contraction toward a line augments the process of frontogenesis.
On the contrary, divergence of the wind from a point or dilation from a line is helpful to the process of frontolysis. Frontolysis, therefore, is likely to occur when fronts move into regions of divergent air flow. That is why on crossing the subtropical high-pressure regions, the fronts generally disappear.
To summarize, when contrasting air masses have convergent movement, the frontogenesis occurs. The temperature contrast in the converging air masses is another most important prerequisite for the process of frontogenesis to occur.
ADVERTISEMENTS:
The fronts come into existence only when the above two conditions are fulfilled simultaneously. In other words, the convergence of air masses with different temperatures and densities is conducive to frontogenesis.
On the contrary, when the air masses move away from each other or when the temperature contrast between the adjacent air masses diminishes due to one reason or the other the fronts dissipate or start decaying. According to Byers, either of the above two conditions may lead to frontolysis.
The regions of cyclonic wind-shift or cyclonic wind shear witness the creation of new fronts. Most of the fronts are associated with troughs of low pressure.
Contrarily, the areas of anticyclonic wind shear do not allow the formation of fronts. Even the pre-existing fronts degenerate in such areas.