– Why does it sometimes become colder in the morning just as the sun comes up?
In: Earth Science
Well, right before the sun comes up is the coldest it gets. The temperature falls continuously after the sun sets, if you account for movement of the air and stored heat in the ground.
The phrase “It’s always darkest before the dawn” isn’t true, but “it’s always coldest before the dawn” is true.
The earth is always losing heat to space, right? So throughout the night it gets colder.
The first second the suns shines on the surface it will deliver just a bit of energy, not enough to compensate for the loss, so it will continue cooling, slower, until the amount of energy given by the sun is equal to the energy lost to space.
In my experience its about 0.5 to 1 hour after sunrise in the tropics, faster in the equator, slower in the poles. But of course there are winds, tides, and other effects that make everything more complicated, but that’s mostly it.
The ground loses heat more readily than the air, so ground level is cooler than at head hight. When the sun rises the ground warms a bit but has a layer of cooler air next to it. As the ground warms it heats the cool air and cause them to rise, thus giving the feeling of cooler air all around until the air normalizes by warming up more.
The opposite of this effect is also true. If you ever visit a beach just as the sun is setting, the water and sand will be perfectly warm from the heat beating down all day.
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