Weather 101: How do thunderstorms form?

Weather 101

The ingredients necessary to produce Mother Nature's fireworks.

We get thunderstorms all the time, but how do they form? Is it the clash of cold and warm air? Is it warm air rising from the surface and forming clouds? Turns out, it’s all of the above!

Thunderstorms are rain showers that produce thunder. All thunderstorms have lightning because it is the lightning that produces the thunder.

To get a thunderstorm, we need 3 key ingredients: moisture, instability, and a lifting mechanism to provide a nudge to develop storms.

Thunderstorm Life Cycle

You may be surprised to hear thunderstorms have life cycles just like us. Obviously, they can’t talk or breathe like you or me, but they do grow, mature, and eventually die.

Developing Stage

Throughout the day, sunlight heats the ground, which then heats the air near the ground. As this air warms, it becomes less dense and begins to rise. As it rises, the air cools and condenses, so clouds begin to form. Over time, a cumulus cloud may form as more air rises from the surface.

This process is the first stage of the thunderstorm life cycle, known as the developing stage. You may also hear it referred to as the cumulus stage by some.

Dominated by an updraft (an upward current of air), the cumulus cloud continues to grow until raindrops form and electric currents in the cloud build up to produce lightning.

Developing thunderstorm in Huntsville on Tuesday, June 15, 2021.

Mature Stage

As more air rises, it continues to fuel the cumulus cloud until it becomes a cumulonimbus cloud (thunderhead cloud). The mature stage is achieved once a downdraft forms (downward current of air) and is balanced with the updraft.

You can actually see the downdraft in thunderstorms. They are typically where precipitation is falling.

Mature thunderstorm from Mount Magazine on Wednesday, June 16, 2021. Image: Chief Meteorologist Dan Skoff

Dissipating Stage

Overtime, the downdraft will overcome the updraft. When this happens, warm & humid air can no longer feed the thunderstorm and the storm will eventually dissipate and die.

Dissipating thunderstorm in Huntsville on Tuesday, June 15, 2021.
Time-lapse from Huntsville Middle School facing south-southeast on the afternoon of Thursday, June 17, 2021 showing the entire thunderstorm life cycle.

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