Eli5: How is it possible that deserts are super hot at day time and below freezing point at night time?
In: Earth Science
No water. Water is a very interesting substance for a variety of reasons, but one of those reasons is that they have a high heat capacity, which is literally the ability to hold a lot of heat energy.
What does that mean? Have you ever noticed how long it takes a simple pot of water to come to a boil, while everything else in your kitchen seems to heat up rather easily? That’s heat capacity. You can put a lot of energy into the water, and the temperature doesn’t go up a lot; and you can take energy out of water without the temperature going down a lot.
What this basically means is that water acts like a “heat battery”. During the day, the sun will heat the water and, during the night, the water will release that heat back into the surrounding landscape.
What this means is that large bodies of water act like nature’s HVAC for the surrounding area. It helps keep a climate moderate.
Now, deserts often occur somewhat far from natural bodies of water. This means that, at night, there are no large bodies of water releasing excess heat into the surrounding environment. On top of that, you don’t have any kind of clouds or weather up above to keep the heat from radiating away.
In other words, because deserts aren’t typically near large bodies of water, don’t receive a lot of rain, don’t typically have any kind of humidity, and don’t have any clouds, they don’t have nature’s heat battery to keep them warm during the night.
All the heat that gets put into them during the day just gets radiated away at night.
Latest Answers