<p>That's because the tropopause, the boundary between the troposphere and stratosphere, is highest in equatorial regions. The high amount energy from the Sun in equatorial regions makes for a lot of convection, which in turn pushes the tropopause to about 16 km above the surface (and sometimes to 18 km) in those equatorial regions. Near the poles, sinking air and reduced solar intensity makes the tropopause much closer to the surface, where it is only 8 km or so high.</p>

<p>The lapse rate in the upper troposphere is roughly the same as the dry adiabatic lapse rate, 9.8 °C/km. The 8 km difference between the tropopause height between equatorial and polar regions results in about 80 degrees more cooling in equatorial regions than polar ones.</p>

CC BY-SA 3.0
2017-03-14T22:07:51.970Z
It may be worth noting that the stratosphere is warmer than the tropopause.
f.thorpe
CC BY-SA 3.0
2017-03-15T01:19:27.773Z
Thank you for this comment. You mean that the height of tropopause varies from the convection. That's interesting for me.
kayak
CC BY-SA 3.0
2017-03-15T01:46:35.980Z
There also be a minimum point at height 25 km in polar regions. This is higher than the tropopause of the equatorial regions. This is opposite to your answer.
kayak
CC BY-SA 3.0
2017-03-15T17:03:16.373Z
@kayak -- The nature of the stratosphere, troposphere, and the boundary between them in polar winter is rather complex. I didn't want to get into that in this answer because you asked a simple question for which there is a simple answer. The complex answer would be the subject of another question.
David Hammen
CC BY-SA 3.0
2017-03-16T10:14:41.583Z
First of all, is tropopuse on 25 km height in polar winter?
kayak
CC BY-SA 3.0
2017-03-16T12:06:42.860Z
@kayak -- No, not by any definition of the tropopause (temperature, dynamic, or ozone). The temperature-based definition is where the lapse rate falls below 2 °K/km rather than where the temperature reaches a minimum. That concept not very useful in Antarctic winter as the tropopause inversion layer is hard to find or non-existent. The engine that drives the tropopause inversion layer is the ozone cycle, which is inactive during polar winter. This is particularly so in the Antarctic, whose winter atmosphere is isolated from the rest of the world by a very long-lived polar vortex.
David Hammen
CC BY-SA 3.0
2017-03-14T13:22:44.093Z
2017-03-14T13:22:44.093Z
David Hammen
<p><a href="https://i.sstatic.net/Hhbbg.png" rel="noreferrer"><img src="https://i.sstatic.net/Hhbbg.png" alt="enter image description here"></a></p>

<p>See this picture from the book <a href="https://books.google.nl/books/about/Global_Physical_Climatology.html?id=RsScBAAAQBAJ&amp;source=kp_cover&amp;redir_esc=y" rel="noreferrer">Hartmann, Dennis L - Global Physical Climatology</a>.<br />
There is a minimum temperature point of 200K at 15km height above the  equator, in June/July/August.</p>

<p>I don't know why this happens. Can anyone explain this?</p>

<meteorology>
Minimum temperature on 15km height on equator in JJA?
kayak
# Minimum temperature on 15km height on equator in JJA?

(Asked by: username_0 on 2017-03-14)

[![enter image description here](https://i.sstatic.net/Hhbbg.png)](https://i.sstatic.net/Hhbbg.png)

See this picture from the book [Hartmann, Dennis L - Global Physical Climatology](https://books.google.nl/books/about/Global_Physical_Climatology.html?id=RsScBAAAQBAJ&source=kp_cover&redir_esc=y).  
There is a minimum temperature point of 200K at 15km height above the equator, in June/July/August.

I don't know why this happens. Can anyone explain this?

**Tags:** meteorology


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## 1 answers

### Answer by username_1 on 2017-03-14. Score: 3

That's because the tropopause, the boundary between the troposphere and stratosphere, is highest in equatorial regions. The high amount energy from the Sun in equatorial regions makes for a lot of convection, which in turn pushes the tropopause to about 16 km above the surface (and sometimes to 18 km) in those equatorial regions. Near the poles, sinking air and reduced solar intensity makes the tropopause much closer to the surface, where it is only 8 km or so high.

The lapse rate in the upper troposphere is roughly the same as the dry adiabatic lapse rate, 9.8 °C/km. The 8 km difference between the tropopause height between equatorial and polar regions results in about 80 degrees more cooling in equatorial regions than polar ones.

> **Comments:**
> **username_2**: It may be worth noting that the stratosphere is warmer than the tropopause.  
> **username_0**: Thank you for this comment. You mean that the height of tropopause varies from the convection. That's interesting for me.  
> **username_0**: There also be a minimum point at height 25 km in polar regions. This is higher than the tropopause of the equatorial regions. This is opposite to your answer.  
> **username_1**: @username_0 -- The nature of the stratosphere, troposphere, and the boundary between them in polar winter is rather complex. I didn't want to get into that in this answer because you asked a simple question for which there is a simple answer. The complex answer would be the subject of another question.  
> **username_0**: First of all, is tropopuse on 25 km height in polar winter?  
> **username_1**: @username_0 -- No, not by any definition of the tropopause (temperature, dynamic, or ozone). The temperature-based definition is where the lapse rate falls below 2 °K/km rather than where the temperature reaches a minimum. That concept not very useful in Antarctic winter as the tropopause inversion layer is hard to find or non-existent. The engine that drives the tropopause inversion layer is the ozone cycle, which is inactive during polar winter. This is particularly so in the Antarctic, whose winter atmosphere is isolated from the rest of the world by a very long-lived polar vortex.  

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