Warm air has a lower density than cool air, so warmer air rises upwards and cooler air settles at the bottom. Clouds form as relatively warmer air, carrying moisture, rises within cooler air. The moist air rises and, as it does so, it cools and some of the water vapor in that rising air condenses. When the moisture condenses, it releases energy known as latent heat of condensation, which allows the rising pocket of air to cool less than the cooler surrounding air, continuing the cloud’s ascension. If enough instability is present in the atmosphere, this process will continue long enough for cumulonimbus clouds to form and produce lightning and thunder. It is cooler by the lake, but watch out for the Chicago Storm.
Chris van Benthuysen, Brad Bolliger