When we turn our face towards the sun on a day with clear skies: Is the heat we feel on our skin actual heat radiation from the surface of the sun or do we just feel the warmth of the molecules in our atmosphere which have been “warmed” by radiation from the upper atmosphere?
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The atmosphere is not as efficient to absorb thermal radiation from the sun, compared to the ground. Plus heat rises, so even if it did warm the upper atmosphere, it wouldn’t efficiently reach your face near the ground. It’s colder in the upper atmosphere, because it doesn’t absorb as much heat from the sun, and the air is thinner. Remember in Iron man, he flew so high his suit began to ice over. Planes are pressurized not just because the air is thinner, but because it’s colder.
The warm air comes from the sun warming the ground, and in turn warming the air. You’ll notice the daily temperatures during sunny days are the warmest not when the sun is at its brightest at noon. The warmest time of day is in the afternoon, because there is a delayed transfer of heat between the ground and the air. If you stand behind a shadow You’ll feel the difference between the heat from the air and the heat from the sun.
The atmosphere is not as efficient to absorb thermal radiation from the sun, compared to the ground. Plus heat rises, so even if it did warm the upper atmosphere, it wouldn’t efficiently reach your face near the ground. It’s colder in the upper atmosphere, because it doesn’t absorb as much heat from the sun, and the air is thinner. Remember in Iron man, he flew so high his suit began to ice over. Planes are pressurized not just because the air is thinner, but because it’s colder.
The warm air comes from the sun warming the ground, and in turn warming the air. You’ll notice the daily temperatures during sunny days are the warmest not when the sun is at its brightest at noon. The warmest time of day is in the afternoon, because there is a delayed transfer of heat between the ground and the air. If you stand behind a shadow You’ll feel the difference between the heat from the air and the heat from the sun.
The heat you feel is radiation from the sun.
Stand in front of a bonfire. You will feel the heat radiation from the fire. Imagine how big and hot a bonfire the sun must be to feel as hot as it does when it’s so far away!
The atmosphere is transparent, which means that it (almost) doesn’t interact with the sun’s light. That’s why sunlight (almost) cannot heat up the atmosphere. Instead, the atmosphere is heated by the earth which is heated by radiation from the sun.
The confusion stems from the fact that “heat” has multiple scientific meanings, but people use them interchangeably in regular speech.
We feel “heat” from molecules in our skin gaining kinetic (movement) energy and jiggling around. But there’s a few ways to make the molecules in your skin jiggle around like that.
When you touch a hot stove, the molecules in the stove are already jiggling around very fast. When they bump into the molecules in your skin, it directly kicks them into moving very fast too, which you feel as heat.
However, you can also make molecules move by transfering energy into them in other ways. Electromagnetic / thermal radiation, for example, carries energy directly. There are almost no molecules in space for the sun to transfer energy to your skin the same way a hot stove does, but radiation can travel through the nothingness of space just fine.
When that radiation travels through the atmosphere and hits the molecules on your skin, some of that energy is absorbed by them, and causes the skin molecules to start jiggling around. And then you feel that as heat.
The heat you feel is radiation from the sun.
Stand in front of a bonfire. You will feel the heat radiation from the fire. Imagine how big and hot a bonfire the sun must be to feel as hot as it does when it’s so far away!
The atmosphere is transparent, which means that it (almost) doesn’t interact with the sun’s light. That’s why sunlight (almost) cannot heat up the atmosphere. Instead, the atmosphere is heated by the earth which is heated by radiation from the sun.
The confusion stems from the fact that “heat” has multiple scientific meanings, but people use them interchangeably in regular speech.
We feel “heat” from molecules in our skin gaining kinetic (movement) energy and jiggling around. But there’s a few ways to make the molecules in your skin jiggle around like that.
When you touch a hot stove, the molecules in the stove are already jiggling around very fast. When they bump into the molecules in your skin, it directly kicks them into moving very fast too, which you feel as heat.
However, you can also make molecules move by transfering energy into them in other ways. Electromagnetic / thermal radiation, for example, carries energy directly. There are almost no molecules in space for the sun to transfer energy to your skin the same way a hot stove does, but radiation can travel through the nothingness of space just fine.
When that radiation travels through the atmosphere and hits the molecules on your skin, some of that energy is absorbed by them, and causes the skin molecules to start jiggling around. And then you feel that as heat.
The heat you feel is infrared radiation which does not require a medium to pass through. That energy is coming directly from the sun as the wavelength is too big to interact with air molecules. As soon as it hits something that can absorb that energy, its temperature will increase.
What’s wild to me is how in daylight the moon’s temperature is around 260F and on the night side, it’s -280F. I’ve never heard of somewhere with such wild temp fluctuations outside of Chicago.
The heat you feel is infrared radiation which does not require a medium to pass through. That energy is coming directly from the sun as the wavelength is too big to interact with air molecules. As soon as it hits something that can absorb that energy, its temperature will increase.
So you get sunburn because the air molecules are so hot they cook your skin? What do you think
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