Thunderstorms are a widespread weather event that occur in every state and all over the world. They are as common as they are widespread. Every year there are over 100,000 thunderstorms that occur in the United States and every day there are over 40,000 thunderstorms that occur throughout the world. Because they are common and considered less of a hazard compared with hurricanes and winter storms, they are often underestimated. This is not helped by the fact that they are difficult to predict primarily because of their short duration and small size. Forecasters do make the attempt to predict thunderstorms by using computer model predictions with data from satellites, pictures, radar displays, ground-based observations and help from local ‘storm spotters.’ Radar is particularly useful because it shows where and how hard it is raining.
Thunderstorms need 3 things to form. They need moisture to form clouds and rain, unstable air that is relatively warm so that it can rise rapidly and some type of lift, like fronts, sea breezes or mountains to help move the air upwards. The process occurs in 3 stages. The first is the cumulus stage in which the sun heats the Earth’s surface and warms the air around it. The warm air then rises and if it is moist it condenses into a cumulus cloud and will continue to grow as long as warm air below it continues to rise. The second stage is the mature stage. When cumulus clouds become large the moisture will become very heavy and rain will start to fall. Now it is a cumulonimbus cloud because of the updraft of warm air, downdraft of cooler air, and the rain. At this point if lightning and thunder occur it is a thunderstorm cell. Lastly is the dissipating stage. At this point the storm has usually been going on for about 30 minutes and the storm starts to dissipate as the downdraft begins to dominate over the updraft keeping warm, moist air from rising. The whole process usually takes an hour.
Although all thunderstorms require the above ingredients and process, they can consist of one thunderstorm cell or many. Single cell thunderstorms are rare because one usually causes the growth of another. A group of cells moving along in a unit, and usually in different stages, is more common and is called a multicluster. Because there are multiple thunderstorm cells in different stages, it can last a few hours. The least common form is called a supercell which has one main updraft moving between 150-175 mph and the updraft rotates which helps to produce extreme weather events like strong hail or violent tornadoes.
All thunderstorms are placed into one of two types; ordinary and severe. Ordinary thunderstorms are more common and last about an hour. They contain rain and sometimes hail. Severe thunderstorms are rarer and more dangerous. They can last up to a few hours and produce baseball-sized hail, strong winds up to 60 mph, intense rains that can cause flash-flooding and tornadoes.
The most common association that people make to thunderstorms is the flash of lightning and the sound of thunder. Lightning is one of the most dangerous parts of a thunderstorm. It kills more people each year then tornadoes. It is produced when voltage differences between ground and atmospheric electrical charges are large enough to overcome the insulating effect of the air. Lightning can occur within the cloud, between clouds, and between the ground and a cloud. A single stroke can heat the air around 30,000 degrees Celsius which causes air to expand at an explosive rate creating a shock wave that turns into a booming sound, formally known as thunder. If you can hear thunder you are close enough to the storm to be struck by lightning.
To avoid being struck go to low lying places away from trees, poles or metal objects. Squat and crouch, don’t lay flat, to make yourself a small target. You should avoid water, phones, and electrical appliances. Not following thunderstorm guidelines you can be struck by lightning which can cause burns, nervous system damage, broken bones and loss of sight or hearing. People that have been struck by lightening can be moved because they hold no electrical charge after being struck.
