The winter solstice is the shortest day of the year – the shortest gap between sunrise and sunset. After the solstice, the days gradually get longer, all the way until summer solstice, in June. But the weather doesn’t begin to warm up right after the solstice. On average, in fact, the coldest days of the year in the United States come in February.

The weather doesn’t immediately respond to the extra sunlight for several reasons. For one thing, there’s still more darkness than daylight. And for another, the Sun is still hovering at a low angle in the sky. That means the atmosphere blocks more of the Sun’s energy than at other times of the year.

Perhaps the biggest factor, though, is the response of the land and oceans. They absorb the Sun’s energy during the longer, warmer times of the year, then release it back into space quite slowly. It’s like putting a roast in the oven. Even after you turn off the heat, the roast continues to get hotter for a while. And when you take it out of the oven, it doesn’t immediately cool off to room temperature – it slowly radiates its heat into the kitchen.

The land cools off more quickly than the oceans. But both of them continue to “cook” the atmosphere for a while as they gradually radiate their heat – a process that continues for weeks. And just the opposite happens after the summer solstice – it takes extra weeks to crank up the heat, creating the oven-like conditions of summer.

Script by Damond Benningfield