The height of tropopause will tend to be higher in?
a) in warmer air mass
b) when the MSL pressure is high
c) at lower level in a warmer air mass
d) both a and b are correct
Answer is d
I understand the warmer air mass part. Since less dense air pushes tropopause higher, but why the high MSL pressure?
Wouldn't higher pressure shrink the airmass and decrease tropopause height?
SARON question
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Re: SARON question
Try this:
Think of FL 180 and flights within the Standard Pressure Region. When the MSL pressure is less than standard, say by 1.00" Hg, at 28.92" Hg, if you are in the Standard Pressure Region, with 29.92 on your pressure sensitive altimeter, ATC cannot assign FL 180 for you, since, when flying at FL 180 with 18,000 feet indicated, you will actually be 1,000 feet LOWER, at 17,000 feet ASL; and aircraft below the Standard Pressure Region, in the Altimeter Setting Region with the current altimeter setting applied, indicating 17,000 feet ASL will also be at 17,000.
Now if this rule about lowest usable flight levels makes sense for you, the rest should fall into place.
Lower pressure puts all of the pressure levels lower, including the tropopause.
And higher pressure puts all of the pressure levels higher.
And we already know the rule for temperatures and pressure levels.
Thus, the tropopause will be LOWER when temperatures are lower or pressures are lower, and HIGHER when the temperatures are higher or pressures are higher.
By the way, it's the same theory for multiple ATPL level questions having anything to do with pressure, flight levels, altimeter settings, tropopause heights etc.
And if you get totally stuck on the SARON/SAMRA written if one of these type of questions appears, you can always revert to the stock memory aid "from high to low ..." to sort out what happens to pressure levels.
One could also get in to air density theory as well but I thought maybe this might be another way to approach the subject.
Think of FL 180 and flights within the Standard Pressure Region. When the MSL pressure is less than standard, say by 1.00" Hg, at 28.92" Hg, if you are in the Standard Pressure Region, with 29.92 on your pressure sensitive altimeter, ATC cannot assign FL 180 for you, since, when flying at FL 180 with 18,000 feet indicated, you will actually be 1,000 feet LOWER, at 17,000 feet ASL; and aircraft below the Standard Pressure Region, in the Altimeter Setting Region with the current altimeter setting applied, indicating 17,000 feet ASL will also be at 17,000.
Now if this rule about lowest usable flight levels makes sense for you, the rest should fall into place.
Lower pressure puts all of the pressure levels lower, including the tropopause.
And higher pressure puts all of the pressure levels higher.
And we already know the rule for temperatures and pressure levels.
Thus, the tropopause will be LOWER when temperatures are lower or pressures are lower, and HIGHER when the temperatures are higher or pressures are higher.
By the way, it's the same theory for multiple ATPL level questions having anything to do with pressure, flight levels, altimeter settings, tropopause heights etc.
And if you get totally stuck on the SARON/SAMRA written if one of these type of questions appears, you can always revert to the stock memory aid "from high to low ..." to sort out what happens to pressure levels.
One could also get in to air density theory as well but I thought maybe this might be another way to approach the subject.
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yowflyer23
- Rank 3
- Posts: 188
- Joined: Mon Aug 02, 2021 6:11 pm
Re: SARON question
Sorry to dig up an old thread, but I’ve been stumped by this question and I don’t get the explanation provided. The tropopause is defined by the lapse rate reducing to zero. It’s not a pressure altitude i.e. FL360. If the MSL pressure was higher, that would imply divergence on the surface, but convergence at altitude resulting in the overall height of the troposphere to reduce. If high MSL pressure was associated with a higher tropopause, wouldn’t the tropopause be higher over the Arctic?
