Violent Storms. Thunderstorms. Convection causes a cumulus cloud to grow into a cumulonimbus cloud. Thunderstorms Three conditions are required for their formation:. Lots of moisture in lower levels of atmosphere
As moisture condenses, it releases latent heat, which keeps a cloud warmer than the air around it, so that it continues its upward motion
2. A mechanism is needed to lift the air
3. The atmosphere must be unstable (the air must continue to cool with increasing altitude so that the growing cloud will stay warmer than its surroundings).
Cumulus stage: warm air rises vertically upwards, condenses and releases latent heat.
Lightning heats the air to 30,000°C; 5 times hotter than the surface of the Sun!Thunder is the sound you hear as this hot air rapidly expands and contracts.
Tornadoes tend to form in the spring during the late afternoon and evening, when the temperature difference between polar air, which still has winter characteristics, and tropical air, which is becoming warmer, are the greatest.
Cyclonic storms continue as long as atmospheric conditions allow warm air to be fed into the system at the surface and removed from the system in the upper atmosphere.