Thunderstorms are a storm that is characterized by the presence of lightning and thunder. They are known by various other names including electrical storms, lightning storms or thundershowers. They Thunderstorms can include heavy rain, sleet, snow or hail and almost always include strong wind. Thunderstorms can occur anywhere in the world but are most common in areas located close to the equator where warm air often collides with cooler fronts.
How does a thunderstorm form?
Thunderstorms are produced by cumulonimbus clouds. For these types of cloud to form three factors are necessary, moisture, an unstable air mass and a lifting force (usually heat). There are a number of factors that can cause this type of cloud to develop. Thermals may be present creating warm updrafts from the Earth’s surface, winds could be converging creating an updraft or wind could be blowing over elevated terrain such as mountain ranges. These triggers cause a rapid upward movement of warm, moist air. As the air travels upwards it becomes cooler and then condenses into water droplets and ice. When the moisture condenses it lets off a chemical energy known as latent heat. This causes the air around the condensing moisture to cool less than that in the cloud which is how a cloud continues to develop. Below the developing storm is a low pressure zone which draws more moisture into the developing storm.
The warm air in the cloud continues to rise until it reaches even warmer air in the atmosphere. At this stage the cloud begins to spread causing the long anvil shape of most thunderstorm clouds. When this occurs the moisture freezes into ice and becomes too heavy to stay suspended in the cloud and it begins to fall through the cloud towards the Earth’s surface. The falling ice melts into water creating droplets of water. These collide with other droplets of water and create a downdraft. This downdraft is what causes the strong winds that accompany thunderstorms. The turbulence caused by the downdrafts and updrafts is also what is responsible for lightning and other severe weather conditions such as tornadoes.
Once the thunderstorm has developed it may stay suspended for a number of hours if the updraft continues to develop or it may dissipate. This occurs when the downdraft overpowers the updraft and no more moist air is drawn into the cloud. When a thunderstorm dissipates it usually rains itself out and ceases to exist or reaches the point where it can develop and updraft again and it reforms.