What conditions must exist for a thunderstorm to form?
abundant source of moisture, air must be lifted so the moisture can dondense, atmosphere must be unstable.
As mosisture condenses, it then.... (1)
Something holds the air up, the moisture condenses and releases latent heat.
Unstable
Air must continue to cool with increasing altitude for the growing cloud to stay warmer than the surrounding air. Air can only rise if it's warmer than the air around it.
The air will keep rising until....
It reaches a stable layer (can't overcome.) Or the the rate of condensation (diminishes with heat) becomes not able to create enough latent heat.
Air-Mass Thunderstorm
Thunderstorm; air rises because of unequal heating of earth's surface within a single air mass and is most common during the afternoon and evening.
Mountain Thunderstorm (air-mass)
Type of air-mass thunderstorm. Occur when an air mass rises as result of orographic lifting.
Sea-breeze Thunderstorm (air-mass)
Are local air-mass thunderstorms caused by extreme temperature differences between the air over land the air over water.
Frontal Thunderstorm
Thunderstorm produced by an advancing cold front.
Three Stages of Thunderstorm
Cumulus stage, Mature stage, and the dissipation stage. Classifed according to the direction in which the air is moving.
Cumulus Stage
Air starts to rise. This creates updrafts; which transport moisture to upper reaches of the cloud. Moisture condenses into cloud droplets and releases latent heat. They coalesce, then fall the earth.
Mature Stage
As precipitation falls, it cools air around it. Cooled air is now more dense, sinks quickly with precipitation; creates downdrafts. Up and downdrafts form convection cell. Equal amount of undrafts and downdrafts.
Dissipation Stage
Production of downdraft is thunderstorm's undoing. As the supply of water runs out, the updrafts stop. Without warm air, updraft cease and precipitation can no longer form.