Posted: Mon Mar 02, 2009 5:51 pm
Thank you, Alex. Your kind of grace is a rare find on the internet.
With that unfortunate contretemps out of the way, I think I owe everyone an explanation about something else I said.
We were all taught in school that Earth is as warm and cozy and life-giving as it is because of its atmosphere. Without the atmosphere, it is often claimed, the Earth would be a cold and lifeless place. Actually, it would be hot on one side and cold on the other, but it would be only vaguely similar to the moon. Hear me out.
The moon presents one face to the sun for something like fourteen days. One side of it gets hot, the other side gets cold. There is nothing on the moon to even out the temperature between the sunlit side and the side in the shadow. If it had a nitrogen atmosphere, it would be only slightly warmer on the dark side and the sunlit side would only be slightly cooler. Why? Because nitrogen is almost completely transparent to sunlight, any convection set up in such a lunar atmosphere would be exceedingly slow.
If we stripped the atmosphere and oceans off the earth and left it exposed to vacuum, it would get hot on the daylight side but, never nearly so hot as it gets on the sunlit side of the moon and it would get cold on the night side, but never so cold as it does on the dark side of the moon. Why? Because the Earth turns on its axis every twenty-four hours. The sunlit side of Earth never receives as much energy as the tidally locked moon and it never gets as much time to cool off as the tidally locked moon.
The idea that the atmosphere is responsible for moderating temperatures on Earth, more specifically the "carbonic acid" in the Earth's atmosphere, originated with a Swedish scientist back in the nineteenth century and I apologize for not being able to recall his name at the moment.
Now, let's confront this notion with something that is well known. Conduction allows heat to move much faster than radiation. And convection is an even better avenue for the flow of heat than direct conduction is. So, how is it that the atmosphere can be wholly responsible for moderating the temperature on our fair planet? By all rights, we should expect "carbonic acid" to help cool the night side of our globe more efficiently than it otherwise would. For that matter, it should be carrying away heat on the day side as well.
It is not the atmosphere that moderates our temperature. It is the oceans that do that job. Of course, we only have oceans this close to the sun because of the atmosphere, but it is not the atmosphere that is responsible for our relatively balmy climate. Without the oceans we would fry in the sun and flash freeze after dark.
Having said that, if the Earth turned on its axis as slowly as Venus does, the Venusian day being somewhat longer than its year, we would be living in a very violent place and ice would likely be hard to find.
Other than keeping the oceans liquid, I don't see how the atmosphere performs as an insulator in any way. From what I can see, it is the water that keeps us warm and keeps us cool.
With that unfortunate contretemps out of the way, I think I owe everyone an explanation about something else I said.
We were all taught in school that Earth is as warm and cozy and life-giving as it is because of its atmosphere. Without the atmosphere, it is often claimed, the Earth would be a cold and lifeless place. Actually, it would be hot on one side and cold on the other, but it would be only vaguely similar to the moon. Hear me out.
The moon presents one face to the sun for something like fourteen days. One side of it gets hot, the other side gets cold. There is nothing on the moon to even out the temperature between the sunlit side and the side in the shadow. If it had a nitrogen atmosphere, it would be only slightly warmer on the dark side and the sunlit side would only be slightly cooler. Why? Because nitrogen is almost completely transparent to sunlight, any convection set up in such a lunar atmosphere would be exceedingly slow.
If we stripped the atmosphere and oceans off the earth and left it exposed to vacuum, it would get hot on the daylight side but, never nearly so hot as it gets on the sunlit side of the moon and it would get cold on the night side, but never so cold as it does on the dark side of the moon. Why? Because the Earth turns on its axis every twenty-four hours. The sunlit side of Earth never receives as much energy as the tidally locked moon and it never gets as much time to cool off as the tidally locked moon.
The idea that the atmosphere is responsible for moderating temperatures on Earth, more specifically the "carbonic acid" in the Earth's atmosphere, originated with a Swedish scientist back in the nineteenth century and I apologize for not being able to recall his name at the moment.
Now, let's confront this notion with something that is well known. Conduction allows heat to move much faster than radiation. And convection is an even better avenue for the flow of heat than direct conduction is. So, how is it that the atmosphere can be wholly responsible for moderating the temperature on our fair planet? By all rights, we should expect "carbonic acid" to help cool the night side of our globe more efficiently than it otherwise would. For that matter, it should be carrying away heat on the day side as well.
It is not the atmosphere that moderates our temperature. It is the oceans that do that job. Of course, we only have oceans this close to the sun because of the atmosphere, but it is not the atmosphere that is responsible for our relatively balmy climate. Without the oceans we would fry in the sun and flash freeze after dark.
Having said that, if the Earth turned on its axis as slowly as Venus does, the Venusian day being somewhat longer than its year, we would be living in a very violent place and ice would likely be hard to find.
Other than keeping the oceans liquid, I don't see how the atmosphere performs as an insulator in any way. From what I can see, it is the water that keeps us warm and keeps us cool.