NORFOLK, Va. — Overnight temperatures are starting to get pretty chilly! Of course, that's not uncommon as we get further into fall. There are a few reasons as to why some nights are cooler than others, but one main reason is the amount of cloud cover in the sky.
Clouds can act as a blanket for the Earth and since they're made up of tiny water droplets or ice crystals, they can reflect and absorb heat. When the sun sets, the Earth's surface cools down as it radiates heat back into the atmosphere. However, clouds trap some of this heat, preventing it from escaping into space. This process is known as the greenhouse effect, where certain gases and clouds retain heat, thus keeping nighttime temperatures higher.
On the other hand, when the sky is clear, there are no clouds to trap the heat. The Earth's surface loses heat rapidly through radiation. Without the insulating effect of clouds, the temperature can drop significantly, leading to cooler nights. This is normally more noticeable in desert regions, where clear skies lead to drastic temperature changes between day and night.
Also, different types of cloud formations can also affect how much heat is retained overnight. When clouds are thick and more low-lying, they tend to be more effective at trapping heat compared to thin, high-altitude clouds.
But if you're curious about the largest 24-hour temperature swing, this actually didn't happen in a desert region. It happened in Loma, Montana as a cold front pushed through and a high pressure was in place. This made way for clear nights and in January of 1972, the town experienced a temperature swing of 103 degrees!
