Why Do We Often See Thunderstorms On Summer Afternoons? | WNYT.com

Why Do We Often See Thunderstorms On Summer Afternoons?

Christina Talamo
Updated: July 15, 2020 01:38 PM
Created: July 15, 2020 01:19 PM

As I’m sure most of you have noticed, when breaking down our daily forecasts lately, we tend to mention the chance for afternoon thunderstorms quite a lot, and it’s not just a coincidence! The possibility for thunderstorms developing in the afternoon hours becomes much more common in the summer season, and here’s why!

Thunderstorm development | Weather.gov Thunderstorm development | Weather.gov
The first major step leading to thunderstorm development is warm air that begins rising rapidly. The key components necessary for a thunderstorm to develop include moisture and instability in the atmosphere, and some type of trigger mechanism to initiate convection. The atmosphere is most unstable when there is much warmer air near the surface and much cooler air at the upper levels of the atmosphere. We call these lifting mechanisms “triggers” because they trigger the atmosphere to start moving, and thus initiate storm development. A few common triggers include fronts passing through, daytime heating, and temperatures cooling at the upper levels. When warm moist air is unstable, it rises and expands. As the air rises rapidly, water vapor within the air starts to cool and thus releases heat. This is when cloud formation occurs, or when we say that condensation has begun. The air condenses forming a cloud, and continues to grow until it becomes a towering cumulus cloud, or what you would notice as your typical storm cloud. Cloud droplets within the cloud then begin to collide with one another, combining to become larger rain droplets, until the droplets are too large and must fall from the cloud as rain. Ice particles within the cloud holding both positive and negative charges can then create lightning, and of course, thunder.

During the summer months, the sun heats air near the surface more rapidly and to higher temperatures throughout the day. The afternoon and evening hours are most conducive for thunderstorm development because this is the time at which radiational heating and instability are maximized. Thunderstorm development is so common on summer afternoons because of this intense daytime heating as well as the high humidity, thus providing the moisture, the instability, and the warm temperatures needed to cause the air to begin rising.

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