During the summer the drama, and sometimes destruction, that comes with summer storms is a regular event, particular in mid latitude countries. Lasting from less than a quarter of an hour to half a day, thunderstorms are associated with warm weather. This is because heat and humidity play a crucial role in their development.
Thunderstorms form in cumulonimbus clouds. These are a towering form of the low lying cumulus clouds. All clouds consist of water vapour but are formed in different ways. Cumulus clouds develop as warm, damp air rises. Temperature affects the density of gases. The gases that form air become increasingly dense as they cool. This mean that warm air is lighter and so moves up. It becomes warmer in the first place usually due to the sun heating the ground or the oceans.
The cumulus cloud becomes classified as a cumulonimbus one when it has grown to a certain size and height. Cumulonimbus clouds are also know simply as thunderclouds. They extend high in the atmosphere with the top in a much colder layer of the atmosphere than the bottom. This is partially responsible for the dramatic weather of thunder, lightning, torrential rain and hail.
The thunder and lightning that define a thunderstorm are the sound and light of electrical activity. At a certain density the particles of a cloud separate into positive and negatively charged areas. The lightning, effectively sparks, most commonly shoots from the negatively charged bottom of the cloud to the positively charged top. It can also shoot from cloud to cloud or cloud to ground.
The heavy rain common during thunderstorms is caused by the condensation of water vapour as the warm, moist air becomes cooled higher in the atmosphere. In some case the droplets freeze before they hit the ground and in the case you have the painful experience of hail.
Eventually the thunderstorm will fade away. This is due to the downdrafts that the storm itself produces cancelling out the rising warm air. As the thunderstorm is losing mass through precipitation in the form of hail or rain it gets smaller and the cloud will also be dissipating.
The most extreme thunderstorms can last a long time before this happens. These supercell thunderstorms can even produce tornadoes and hurricanes.
The conditions for thunderstorms of any kind to form are most likely to occur in the summer, which is a time you should be keeping an eye on weather forecasts. Thunderstorms can be exciting to watch but are also potentially dangerous and damaging. Preparation can make all the difference to whether your property is damaged or not by the summer storms.
