How Thunderstorms Form
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The Cumulus Stage
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Thunderstorms form in three stages. The first stage is known at the "cumulus stage." This begins with a small trigger, which can be thermals created from insulation heating in the ground or winds blown across various elevations of terrain. The winds ultimately force masses of moisture upwards into the air. As it gets higher, the moisture cools and begins to form tiny drops of water. These drops of water form cumulus clouds. The condensation process releases heat into the surrounding air. This heat, in turn, causes an updraft and creates a low-pressure zone beneath the clouds.
The Mature Stage
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The second stage of a thunderstorm is called the "mature stage." This occurs when the air cannot rise any farther. The cumulus clouds become cumulonimbus incus clouds. The tiny water droplets in the cloud combine into larger droplets which then freeze into ice. The ice is too heavy to remain in the cloud, and so falls to the ground, melting into raindrops as it descends into warmer air. If there is an especially strong updraft, the ice particles remain aloft for a longer period of time and may not melt before reaching the ground. This creates hail. The falling precipitation creates a downdraft. The simultaneous updrafts and downdrafts create turbulence resulting in strong winds, thunder, and lightning.
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Lightning and Thunder
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Lightning and thunder are the most noticeable hallmarks of a thunderstorm. When there is a high buildup of static electrical charges within the storm, it can spark. Storms tend to have high concentrations of both positive and negative electrical charges. The opposite charges are attracted to each other and will eventually cause a discharge seen as lightning. Lightning can occur between two clouds, between a cloud and the air, or between the cloud and the ground. About 80% of lighting occurs within the cloud, while only 20% connects with the ground. The extreme heat of a bolt of lighting (around 54,000 degrees F) causes the surrounding air to rapidly expand and contract. This creates the sound vibrations we hear as thunder.
The Dissipating Stage
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The final stage of a thunderstorm is the "dissipating stage." This occurs when the final downdraft is pushed to the ground. The cool air carried along with it cuts off the updrafts. This causes the storm to dissipate. The dissipating stage can occur as soon as twenty minutes into the mature stage. The majority of thunderstorms peak after about 15 to 30 minutes, though some can last as long as two hours.
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