Adiabatic lapse Rate

Mavmb · February 23rd, 2004, 23:08

It's 3 degrees per 1000 feet. Now, just for personal knowledge, why is this important at all? I don't understand what adiabatic really means and how it causes weather or how it is significant to clouds or turbulence. Any takers on that question?

Doug Taylor · February 23rd, 2004, 23:11

I think it just gives you a very rough method of approximating temperature.

Plus, there needs to be a standard temperature deviation from sea level/59F/15C at various altitudes.

But that's just off the top of my head.

jetman · February 23rd, 2004, 23:31

Adiabatic means that the temp in the raising air changes withot adding or taking away heat from outside the parcel of air [ air rises, press decreases ,temp decreases] if air sinks it will be compressed by increassing pressure ,temp will rise

mtsu_av8er · February 24th, 2004, 00:16

[in my best Samuel L. Jackson voice...] : Check out the big brain on Jetman!!!

pilot602 · February 24th, 2004, 08:20

It also serves as a way to determine the stability of an airmass. If the lapse rate of the airmass in question is higher than the average lapse rate it will be an unstable mass. If it's lower than the average the airmass will tend to be stable. I may have that backwards but I'm pretty sure that's correct. I'll go check around ...

cime_sp · February 24th, 2004, 08:51

Be careful about that though...there is a dry lapse rate and a moist lapse rate. I believe the moist lapse rate is less because water doesn not cool as quickly as air

kellwolf · February 24th, 2004, 09:42

I've used it to get a rough in-air estimate of where the freezing level might be. Granted, that's pretty high up in Florida....

E_Dawg · February 24th, 2004, 10:52

Adiabatic lapse rate is not the same as environmental lapse rate (actual lapse rate).

I dunno how much knowing the adiabatic lapse rate helps in practice since there isn't really a way to figure it out that I know of. It's 3 for dry air and around 1.5 for moist air...

But the environmental lapse rate is important because it gives a rough measure of air stability; i.e. >2/1000'=unstable and <2/1000'=stable.

Think of an inversion, there's a negative lapse rate and very stable air. When figuring out freezing levels, etc. use 2/1000' because that's the standard lapse rate.

Mavmb · February 24th, 2004, 11:41

[ QUOTE ]
Be careful about that though...there is a dry lapse rate and a moist lapse rate. I believe the moist lapse rate is less because water doesn not cool as quickly as air

[/ QUOTE ]

Water doesn't cool as quickly as air. Thanks. Than that makes sense why the dry lapse rate is 3 degrees per 1000 feet. The standard is 2 degrees celsius per 1000 feet. There's an examiner that asks about the adiabatic lapse rate (3 per 1000) and I just wondered what the adiabatic rate affects. Maybe it's just one of those examiner questions. Me thinks we need a meteorologist here.

Ophir · February 25th, 2004, 18:41

I hope mtsu doesn't ridicule me for this one: HA

Adiabatic is really important when it comes down to undestanding meterology. Adiabatic spefically means the NO heat is exchanged with the surrounds of the gas or liquid. Yes, air cools as it rises but this is due to the amount of expansion or compression that parcel of air is allowed in that gain in altitude. Always think in terms of that and it will help; if a gas expands, it cools. Conversely, if it compresses it is heated. All this is due to how tightly knit the molecules are.

If you were to take a parcel of air and lift it will expand at nearly the same rate the atmosphere expands. If you were to measure the temperture along the way you would get its lapse rate. I won't go further unless it is warranted, andI am about to be late for the muuvvvie.

mtsu_av8er · February 25th, 2004, 19:41

[ QUOTE ]
I hope mtsu doesn't ridicule me for this one: HA

[/ QUOTE ]

bluelake · February 25th, 2004, 21:15

I just took out my trusty balloon and squeeeeeezed it really hard. It got warm!

mtsu_av8er · February 25th, 2004, 21:20

[ QUOTE ]
I just took out my trusty balloon and squeeeeeezed it really hard. It got warm!

[/ QUOTE ]

Don't pop it....

chris · March 1st, 2004, 06:49

To add to this super interesting discussion

....

The moist lapse rate is less because as the water vapour condenses, it is releasing latent heat. This release of heat, which always occurs with condensation, causes the moist lapse rate to be slightly less. Meteorologists use the dry lapse rate when the parcel has yet to condense. Once clouds begin to form, the parcel is cooling at the moist rate.

sixpack · March 7th, 2004, 07:37

You're forcing me to strain my already impared memory, but I think this the the model I used back in my IFR checkride days.

Air with a low lapse rate will cool of slowly as it rises (i.e. stays warmer at altitude). Because it is warmer than the surrounding air, it will continue to rise.

Rising air means less stable air.

February 23rd, 2004, 23:08	#1
Mavmb Old Skool Join Date: Feb 2002 Location: Phoenix, AZ Posts: 2,169	Adiabatic lapse Rate It's 3 degrees per 1000 feet. Now, just for personal knowledge, why is this important at all? I don't understand what adiabatic really means and how it causes weather or how it is significant to clouds or turbulence. Any takers on that question?

February 23rd, 2004, 23:11	#2
Doug Taylor Agent Smith Join Date: Dec 1969 Location: KSDL Posts: 41,186 Blog Entries: 1	Re: Adiabatic lapse Rate I think it just gives you a very rough method of approximating temperature. Plus, there needs to be a standard temperature deviation from sea level/59F/15C at various altitudes. But that's just off the top of my head.

February 23rd, 2004, 23:31	#3
jetman Junior Member Join Date: Jul 2003 Posts: 188	Re: Adiabatic lapse Rate Adiabatic means that the temp in the raising air changes withot adding or taking away heat from outside the parcel of air [ air rises, press decreases ,temp decreases] if air sinks it will be compressed by increassing pressure ,temp will rise

February 24th, 2004, 00:16	#4
mtsu_av8er Old Skool Join Date: Dec 2002 Location: Utopia Posts: 12,567	Re: Adiabatic lapse Rate [in my best Samuel L. Jackson voice...] : Check out the big brain on Jetman!!!

February 24th, 2004, 08:20	#5
pilot602 Old Skool Join Date: Oct 2001 Location: who haa Posts: 3,750	Re: Adiabatic lapse Rate It also serves as a way to determine the stability of an airmass. If the lapse rate of the airmass in question is higher than the average lapse rate it will be an unstable mass. If it's lower than the average the airmass will tend to be stable. I may have that backwards but I'm pretty sure that's correct. I'll go check around ...

February 24th, 2004, 08:51	#6
cime_sp Senior Member Join Date: Oct 2002 Location: ATL Posts: 782	Re: Adiabatic lapse Rate Be careful about that though...there is a dry lapse rate and a moist lapse rate. I believe the moist lapse rate is less because water doesn not cool as quickly as air

February 24th, 2004, 09:42	#7
kellwolf Old Skool Join Date: Jun 2003 Location: Memphis, TN Posts: 13,860	Re: Adiabatic lapse Rate I've used it to get a rough in-air estimate of where the freezing level might be. Granted, that's pretty high up in Florida....

February 24th, 2004, 10:52	#8
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,233	Re: Adiabatic lapse Rate Adiabatic lapse rate is not the same as environmental lapse rate (actual lapse rate). I dunno how much knowing the adiabatic lapse rate helps in practice since there isn't really a way to figure it out that I know of. It's 3 for dry air and around 1.5 for moist air... But the environmental lapse rate is important because it gives a rough measure of air stability; i.e. >2/1000'=unstable and <2/1000'=stable. Think of an inversion, there's a negative lapse rate and very stable air. When figuring out freezing levels, etc. use 2/1000' because that's the standard lapse rate.

February 24th, 2004, 11:41	#9
Mavmb Old Skool Join Date: Feb 2002 Location: Phoenix, AZ Posts: 2,169	Re: Adiabatic lapse Rate [ QUOTE ] Be careful about that though...there is a dry lapse rate and a moist lapse rate. I believe the moist lapse rate is less because water doesn not cool as quickly as air [/ QUOTE ] Water doesn't cool as quickly as air. Thanks. Than that makes sense why the dry lapse rate is 3 degrees per 1000 feet. The standard is 2 degrees celsius per 1000 feet. There's an examiner that asks about the adiabatic lapse rate (3 per 1000) and I just wondered what the adiabatic rate affects. Maybe it's just one of those examiner questions. Me thinks we need a meteorologist here.

February 25th, 2004, 18:41	#10
Ophir Senior Member Join Date: Mar 2002 Location: was Ophir, CO, now in SLC! Posts: 1,481	Re: Adiabatic lapse Rate I hope mtsu doesn't ridicule me for this one: HA Adiabatic is really important when it comes down to undestanding meterology. Adiabatic spefically means the NO heat is exchanged with the surrounds of the gas or liquid. Yes, air cools as it rises but this is due to the amount of expansion or compression that parcel of air is allowed in that gain in altitude. Always think in terms of that and it will help; if a gas expands, it cools. Conversely, if it compresses it is heated. All this is due to how tightly knit the molecules are. If you were to take a parcel of air and lift it will expand at nearly the same rate the atmosphere expands. If you were to measure the temperture along the way you would get its lapse rate. I won't go further unless it is warranted, andI am about to be late for the muuvvvie.

February 25th, 2004, 19:41	#11
mtsu_av8er Old Skool Join Date: Dec 2002 Location: Utopia Posts: 12,567	Re: Adiabatic lapse Rate [ QUOTE ] I hope mtsu doesn't ridicule me for this one: HA [/ QUOTE ]

February 25th, 2004, 21:15	#12
bluelake Senior Member Join Date: Dec 2001 Location: Redding, CA Posts: 619	Re: Adiabatic lapse Rate I just took out my trusty balloon and squeeeeeezed it really hard. It got warm!

February 25th, 2004, 21:20	#13
mtsu_av8er Old Skool Join Date: Dec 2002 Location: Utopia Posts: 12,567	Re: Adiabatic lapse Rate [ QUOTE ] I just took out my trusty balloon and squeeeeeezed it really hard. It got warm! [/ QUOTE ] Don't pop it....

March 1st, 2004, 06:49	#14
chris Junior Member Join Date: Jul 2000 Location: Canada Posts: 291	Re: Adiabatic lapse Rate To add to this super interesting discussion .... The moist lapse rate is less because as the water vapour condenses, it is releasing latent heat. This release of heat, which always occurs with condensation, causes the moist lapse rate to be slightly less. Meteorologists use the dry lapse rate when the parcel has yet to condense. Once clouds begin to form, the parcel is cooling at the moist rate.

March 7th, 2004, 07:37	#15
sixpack Junior Member Join Date: Jul 2003 Location: Portland, Oregon Posts: 277	Re: Adiabatic lapse Rate You're forcing me to strain my already impared memory, but I think this the the model I used back in my IFR checkride days. Air with a low lapse rate will cool of slowly as it rises (i.e. stays warmer at altitude). Because it is warmer than the surrounding air, it will continue to rise. Rising air means less stable air.

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