Since last week’s article generated a lot of interest and requests for more information, I decided to write a follow-up on the previous article. The point of the article was to demonstrate that the seasonal temperature response varies by altitude. So different are the responses that it is clear that the troposphere and the stratosphere are responding to different inputs. The temperature of the troposphere is primarily driven by the combination of geography and season at the Earth’s surface. The stratospheric temperature is driven by the daily energy the Earth gets from the Sun as dictated by the distance the Earth is from the Sun. You can look back at the previous article for more details.
One request that I thought was interesting was to build a seasonal temperature of the entire atmosphere. The first step is to show the average temperature profile of the atmosphere by altitude. I will simply use one of NOAA’s charts for this purpose.
This will be useful because it can be compared to the seasonal profile of the different altitudes.
Below is the seasonal temperature profile for 7 different altitudes.
This is a rather huge graphic and the best way to view it is to open the picture in a new window and the zoom in. That is the only way to get the full resolution. This full profile provides some fascinating insight into how the atmosphere behaves.
The Troposphere shows the same seasonal behavior as the Earth’s surface. It is coolest when the Northern Hemisphere is experiencing winter and warmest when it is in summer. This is driven by the geological differences between the two hemispheres. The higher land/ocean ratio in the NH results in greater temperature swings for both the winter and the summer. This is discussed in more detail in the book.
In the 14-21km altitude there is almost no seasonal temperature variation. I fixed the temperature range to 3.0 °C (except the 41km which is 3.5 °C) so the relative swings can be compared to each other. This region is also the coldest region of the atmosphere. The idea that such a colder region is somehow transferring the energy needed to warm the stratosphere cannot be supported by any thermodynamic analysis. That this ~7km region shows no seasonal temperature swing simply verifies that fact. There is no significant energy transfer taking place between the troposphere and the stratosphere.
Above 25km it is clear that the behavior is exactly what was shown in the last article. The total energy that the Earth gets from the Sun (which is dictated by the distance from the Sun since the solar output should be taken as a constant) is what drives the seasonal temperature changes there. There is simply no other mechanism that can explain the seasonal response of the stratosphere. In a few thousand years the peak stratospheric temperature will be in March as that is when the Earth will be closest to the Sun. Stratospheric temperatures are directly linked to the Earth’s orbital precession.
This is simply one more piece of the puzzle that supports the importance of the Earth’s orbit and the impact that orbital changes have on the energy balance. Just one more demonstration that Milankovitch was correct in his theory that it is orbital behavior, not gases that drive the glacial/interglacial cycles. When the expanded theory that I describe in my book is applied to the past few thousand years, the behavior is crystal clear.