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Archive 1 |
To quote from the article itself "The varying environmental lapse rates across the earth surface are of critical importance in meteorology." Why does the Met Project rate is as low? JMcC 14:56, 13 September 2006 (UTC)
Why isn't this article called Lapse rate? The adiabatic is just one of the lapse rates that the article describes. The environmental lapse rate in particular is not adiabatic. It is the actual change in temperature with height. JMcC 14:42, 13 September 2006 (UTC)
It seems to me that adiabatic lapse rate and lapse rate now strongly overlap. Should we merge them, or at least refactor them into 2 distinct articles? hike395 22:00, 16 September 2006 (UTC)
A lapse rate is also an important metric in various fields of insurance. Presently I'm not seeing anything about lapse rates on any of the insurance pages either, but maybe a link to the insurance category would be a good idea.
I cannot open the External Links. Do they work? -- Natasha2006 14:16, 16 April 2007 (UTC)
I will give you all until June 20 to add inline references per the Wikipedia Guide of Style, at least one per paragraph. If not, I will downgrade the article to Start. Thegreatdr 20:45, 18 May 2007 (UTC)
Is the lapse rate truly defined by professionals as the slope, -(T2-T1)/(z2-z1), rather than the derivative -dT/dz? 76.120.154.6 14:44, 30 September 2007 (UTC)
The lapse rates are always presented as some temperature change per altitude change. For example, 9.78 degrees per 1000 metres. Is this really constant? It would seem to me that it is the change of temperature with pressure change that would be constant and that since the pressure drop over a 1000 metre altitude change decreases with altitude, that the lapse rate with respect to altitude change would not be constant. Sancho McCann 05:15, 1 December 2006 (UTC)
Actually, for completeness, would it be worth mentioning dry lapse rate as a function of pressure?? It isn't necessary for understanding of the term and a 9.78 per km is a really close approximation as mentioned above. There's a good description on a lecture slide here: http://www.sparc.sunysb.edu/atm205/fall2001/lecture7/sld004.htm. What do you think? Sancho McCann 19:40, 1 December 2006 (UTC)
Here is an alternative simpler way, the same as the German page uses, to calculate the lapse rate for rock in the earth interior. [1] and it only depends on specific heat capacity which is almost the same for air and rock. Davidjonsson Davidjonsson 23:30, 1 December 2007 (UTC)
Can anyone comment on why the lapse rate has the value it does? The atmosphere is a complicated and dynamic system: There's convection, radiation, heating by the ground, etc. But it is universally true that higher altitudes are colder. My hunch is that gravity is the fundamental mechanism. I'm interested to know how an ideal gas behaves at equilibrium in a gravitational field. My guess is that it would end up with a temperature gradient equal to the adiabatic lapse rate 9.78 °C/km, otherwise parcels of air would generate energy by trading altitudes. I'll leave with the comment that 9.78°C/km is on the order of M g/ kB (34°C/km), where M is the mass of an air molecule (29 u). That is the lapse rate you'd get by making the naive assumption that kBT increases by the amount of energy gained as a molecule "falls" to lower altitude. I think the article would benefit from a statement about the fundamental reason it is colder up there. Spiel496 03:01, 20 July 2007 (UTC)
I have just posted a revision about the changing temperature with height in the troposphere on [ atmosphere] the explanation for the change is available at the end of this contribution [ Talk: Earth's Atmosphere]. To sumarise: heated air expands and rises by convection (its density is reduced by expansion), it rises against the force of gravity, gaining gravitational potential energy as it does so. Thus some of its thermal (kinetic) energy is converted into gravitational potential energy - the gas cools.
As does this article, the NASA website of the link this website give this formula dP = -gρ dz as part of the calculation for the lapse rate: the density (ρ) is taken as a constant with height, this is selfevidently not the case, ρ is f(z), it results in a Lapse rate that is constant with height and far too high, 9.5K/km instead of 6.5K/km.
There are other problems with this article, the mathematical convenience of using a constant density just happens to eliminate an important amospheric property, the expansion of the air with reduced pressure! -- Damorbel ( talk) 15:21, 3 July 2008 (UTC)
please can someone with expertise in this matter expand this article for the general reader. The concept of 'it gets colder as you go up because the pressure reduces and gas cools as it expands' is quite simple. Surely someone can work something like that into the article? Maybe you can add some examples of cirrus clouds forming as air cools due to lapse rate? Andrewjlockley ( talk) 01:39, 1 July 2009 (UTC)
No one seems to mention that perhaps the driving force to many atmospheric events is the fact that moist air absorbs infrared energy from the sun while dry air transmits it.
Here are some links: John_Tyndall
http://www.emeraldinsight.com/fig/0870250407011.png
http://www.stormingmedia.us/93/9388/A938881.html
Arydberg (
talk)
16:07, 22 August 2009 (UTC)
My source for the wet adiabatic lapse rate equation is page 178 of An Introduction to Thermal Physics by Daniel V. Schroeder. Publisher: Addison Wesley Longman. Copyright 2000.
User:kloddant 9/5/09 —Preceding undated comment added 16:34, 5 September 2009 (UTC).
Is it possible that the examples in the 'Significance in meteorology' section have been exchanged? There are three scenario's: the environmental lapse rate is either less than the moist rate, between moist and dry, or larger than dry. However, if the environmental lapse rate is small as in the first case (it is defined to be positive for a decrease, so small means close to zero and probably positive), that means that is cools little (or even heats) with increasing altitude. Now the example says 'rising air will cool faster than the surrounding air', but from what I understand the exact opposite happens? It would fit the description in the third scenario: 'a parcel of air will gain buoyancy as it rises both below and above the lifting condensation level or convective condensation level'. Please excuse me if I'm wrong, I'm not an atmosphere scientist or anything, it just confused me. Mverleg ( talk) 21:23, 31 October 2010 (UTC)
The erticle was edited on April 25th to include this:
It says that M is the mass of a mole of air but the number given is the mass of a mole of water. Would someone correct the Lapse rate accordingly? Thanks, mbeychok
where: | |
= Wet adiabatic lapse rate, K/m | |
= Earth's gravitational acceleration = 9.8076 m/s2 | |
= Heat of vaporization of water, J/kg | |
= The ratio of the mass of water vapor to the mass of dry air, kg/kg | |
= The universal gas constant = 8,314 J kmol-1 K-1 | |
= The molecular weight of any specific gas, kg/kmol = 28.964 for dry air and 18.015 for water vapor | |
= The specific gas constant of a gas, denoted as | |
= Specific gas constant of dry air = 287 J kg-1 K-1 | |
= Specific gas constant of water vapor = 462 J kg-1 K-1 | |
=The dimensionless ratio of the specific gas constant of dry air to the specific gas constant for water vapor = 0.6220 | |
= Temperature of the saturated air, K | |
= The specific heat of dry air at constant pressure, J kg-1 K-1 |
The derivation of the dry adiabatic lapse rate is not understandable since not all symbols are defined.I think that for an average reader the names of all symbols should be given. — Preceding unsigned comment added by FrankBerninger ( talk • contribs) 07:04, 19 October 2011 (UTC)
There are several paragraphs repeated under "Mathematical definition" that are already under "Definition". Jon Stephen Horridge ( talk) 12:08, 4 April 2012 (UTC)
Conversions should be provided for non-metric users. Aviation users in particular need to know feet/F rather than km/C for the dry adiabatic lapse rate.
UPDATE FOR PILOTS. In Europe we use the JAA as the aviation authority, and they state and test that the SALR is 0.6C/100m for the purpose of the ATPL exams. Very seldom do instructors and very seldom in the exams now will you see the SALR as c/ft. (1.8C/1000ft).-- Pugzi 08:29, 15 May 2006 (UTC) (Steve Francis)
British english calls this a slew rate rather than lapse rate. I found this article a little difficult to find due to different terminology. Are we able to put in a redirection?
Tony Wallace — Preceding unsigned comment added by 122.58.21.179 ( talk) 07:04, 22 June 2013 (UTC)
The formula given in the article is:
Substituting numerical values, this expands to:
The prefactor looks good since this is the same as the dry adiabatic lapse rate. However, when I run some numbers, the results don't look reasonable:
The article says that the moist adiabiatic lapse rate is typically around 5 °C/km, and many other sites on the internet seem to support that.
If I had to guess the problem is actually with that second dimensionless r, and the formula should be:
So that are squared together in the denominator. In that case, the numerical expansion is:
Which then gives:
However, guessing is not really a good solution. So could someone please try to verify / derive the formula to figure out what the correct expression is. Dragons flight ( talk) 20:21, 13 September 2013 (UTC)
The notation °C was recently (Nov. 16) changed to C° throughout. If this is standard for relative temperatures I'm happy to leave it as is, if not I'll either revert it or change it to K as people prefer. Vaughan Pratt ( talk) 23:33, 1 March 2015 (UTC)
It starts well enough - A formal definition from the Glossary of Meteorology is:
.... and then immediately degrades into fantasy
The atmosphere isn't "warmed by conduction..."; if it was, the temperature at a few metres above the surface would be very low. Air is a good insulator. Neither has lapse rate anything to do with "parcels of air".
The discussion for Dry adiabatic lapse rate contradicts itself immediately. After stating that
which is of course correct, and
which also is correct and contradicts the earlier "warmed by conduction...". it goes on to state
"loses internal energy" must mean loss of kinetic energy, which means that the process as described in this article is not adiabatic.
I've found similar descriptions on many (most?) university websites, all discussing "rising parcels of air", occasionally envisaging an "invisible container" which has "work done on it" by the "expanding air".
The lapse rate is a characteristic of Earth's atmosphere whether "parcels of air" rise, fall or dance a jig. Those imaginary "parcels" are expanding into an atmosphere whose temperature (in the troposphere) and pressure decrease with height; in other words, an existing set of conditions. This article doesn't address the reason(s) for those conditions, and so is fundamentally flawed. Rambler24 ( talk) 18:32, 1 March 2013 (UTC)
The relationship between temperature and pressure is nearly fixed (it'll vary as the composition of the atmosphere changes, but presumably not by much). However, the relationship between pressure and altitude is not so nearly fixed, since it depends on the density profile over altitude, which depends on temperature over altitude (and also on humidity over altitude, to some extent).
The relationship of temperature and pressure is
The here is not the same as the gamma used in the article body to denote lapse rate. The usage in the article is unfortunate, since is usually used to denote the specific heat ratio, see adiabatic. Is the article's usage standard?
The pressure in the atmosphere drops off approximately exponentially with altitude. This means a 1000m increase in elevation typically produces a 12.6% drop in pressure. That drop in pressure would cause a 3.45% drop in temperature, which is about 10 C.
In any case, my point is that pressure at altitude varies, and varies with some independence from the pressure at sea level directly below, and as a result the dry adiabatic lapse rate is not a constant.
Iain McClatchie 18:34, 1 October 2005 (UTC)
Ok, it's not strictly constant, but it does turn out to be vary remarkably little if you do the numerical integration.
Customarily, undergraduates are shown the simple derivation giving the dry lapse rate of -g K/km, or -9.86K/km. This at ground/sea level. Once water vapour is present the figure is 6.5K/km. The potential temp greatly increases with altitude, of course. 27.33.81.127 ( talk) 06:20, 1 February 2016 (UTC)
"For example, there can be an inversion layer in which the temperature increases with altitude."
I think I am correct in saying that the temperature does not necessarily need to increase in temperature to be described as an "inversion." If the lapse rate drop below the standard lapse rate this is also called an inversion because this is the boundary where major meterological behavior ceases because the air has no excess temperature derived kinetic energy and stops rising. (It may still have horizontal kinetic energy - wind.) Most atmospheric inversions are not strict inversions and this can be very confusing nomenclature for people when they see a measured lapse rate chart on a day "with an inversion" and there is no temperature reversal illustrated. I've done no editing but feel free to do so. Anyone who rewrites relevant sections should incorporate some of the above using filled in lapse rate charts as an illustrative tool. Ecstatist ( talk) 04:17, 2 December 2016 (UTC)
Please relate this to the article. Biggerj1 ( talk) 08:27, 26 June 2018 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
To quote from the article itself "The varying environmental lapse rates across the earth surface are of critical importance in meteorology." Why does the Met Project rate is as low? JMcC 14:56, 13 September 2006 (UTC)
Why isn't this article called Lapse rate? The adiabatic is just one of the lapse rates that the article describes. The environmental lapse rate in particular is not adiabatic. It is the actual change in temperature with height. JMcC 14:42, 13 September 2006 (UTC)
It seems to me that adiabatic lapse rate and lapse rate now strongly overlap. Should we merge them, or at least refactor them into 2 distinct articles? hike395 22:00, 16 September 2006 (UTC)
A lapse rate is also an important metric in various fields of insurance. Presently I'm not seeing anything about lapse rates on any of the insurance pages either, but maybe a link to the insurance category would be a good idea.
I cannot open the External Links. Do they work? -- Natasha2006 14:16, 16 April 2007 (UTC)
I will give you all until June 20 to add inline references per the Wikipedia Guide of Style, at least one per paragraph. If not, I will downgrade the article to Start. Thegreatdr 20:45, 18 May 2007 (UTC)
Is the lapse rate truly defined by professionals as the slope, -(T2-T1)/(z2-z1), rather than the derivative -dT/dz? 76.120.154.6 14:44, 30 September 2007 (UTC)
The lapse rates are always presented as some temperature change per altitude change. For example, 9.78 degrees per 1000 metres. Is this really constant? It would seem to me that it is the change of temperature with pressure change that would be constant and that since the pressure drop over a 1000 metre altitude change decreases with altitude, that the lapse rate with respect to altitude change would not be constant. Sancho McCann 05:15, 1 December 2006 (UTC)
Actually, for completeness, would it be worth mentioning dry lapse rate as a function of pressure?? It isn't necessary for understanding of the term and a 9.78 per km is a really close approximation as mentioned above. There's a good description on a lecture slide here: http://www.sparc.sunysb.edu/atm205/fall2001/lecture7/sld004.htm. What do you think? Sancho McCann 19:40, 1 December 2006 (UTC)
Here is an alternative simpler way, the same as the German page uses, to calculate the lapse rate for rock in the earth interior. [1] and it only depends on specific heat capacity which is almost the same for air and rock. Davidjonsson Davidjonsson 23:30, 1 December 2007 (UTC)
Can anyone comment on why the lapse rate has the value it does? The atmosphere is a complicated and dynamic system: There's convection, radiation, heating by the ground, etc. But it is universally true that higher altitudes are colder. My hunch is that gravity is the fundamental mechanism. I'm interested to know how an ideal gas behaves at equilibrium in a gravitational field. My guess is that it would end up with a temperature gradient equal to the adiabatic lapse rate 9.78 °C/km, otherwise parcels of air would generate energy by trading altitudes. I'll leave with the comment that 9.78°C/km is on the order of M g/ kB (34°C/km), where M is the mass of an air molecule (29 u). That is the lapse rate you'd get by making the naive assumption that kBT increases by the amount of energy gained as a molecule "falls" to lower altitude. I think the article would benefit from a statement about the fundamental reason it is colder up there. Spiel496 03:01, 20 July 2007 (UTC)
I have just posted a revision about the changing temperature with height in the troposphere on [ atmosphere] the explanation for the change is available at the end of this contribution [ Talk: Earth's Atmosphere]. To sumarise: heated air expands and rises by convection (its density is reduced by expansion), it rises against the force of gravity, gaining gravitational potential energy as it does so. Thus some of its thermal (kinetic) energy is converted into gravitational potential energy - the gas cools.
As does this article, the NASA website of the link this website give this formula dP = -gρ dz as part of the calculation for the lapse rate: the density (ρ) is taken as a constant with height, this is selfevidently not the case, ρ is f(z), it results in a Lapse rate that is constant with height and far too high, 9.5K/km instead of 6.5K/km.
There are other problems with this article, the mathematical convenience of using a constant density just happens to eliminate an important amospheric property, the expansion of the air with reduced pressure! -- Damorbel ( talk) 15:21, 3 July 2008 (UTC)
please can someone with expertise in this matter expand this article for the general reader. The concept of 'it gets colder as you go up because the pressure reduces and gas cools as it expands' is quite simple. Surely someone can work something like that into the article? Maybe you can add some examples of cirrus clouds forming as air cools due to lapse rate? Andrewjlockley ( talk) 01:39, 1 July 2009 (UTC)
No one seems to mention that perhaps the driving force to many atmospheric events is the fact that moist air absorbs infrared energy from the sun while dry air transmits it.
Here are some links: John_Tyndall
http://www.emeraldinsight.com/fig/0870250407011.png
http://www.stormingmedia.us/93/9388/A938881.html
Arydberg (
talk)
16:07, 22 August 2009 (UTC)
My source for the wet adiabatic lapse rate equation is page 178 of An Introduction to Thermal Physics by Daniel V. Schroeder. Publisher: Addison Wesley Longman. Copyright 2000.
User:kloddant 9/5/09 —Preceding undated comment added 16:34, 5 September 2009 (UTC).
Is it possible that the examples in the 'Significance in meteorology' section have been exchanged? There are three scenario's: the environmental lapse rate is either less than the moist rate, between moist and dry, or larger than dry. However, if the environmental lapse rate is small as in the first case (it is defined to be positive for a decrease, so small means close to zero and probably positive), that means that is cools little (or even heats) with increasing altitude. Now the example says 'rising air will cool faster than the surrounding air', but from what I understand the exact opposite happens? It would fit the description in the third scenario: 'a parcel of air will gain buoyancy as it rises both below and above the lifting condensation level or convective condensation level'. Please excuse me if I'm wrong, I'm not an atmosphere scientist or anything, it just confused me. Mverleg ( talk) 21:23, 31 October 2010 (UTC)
The erticle was edited on April 25th to include this:
It says that M is the mass of a mole of air but the number given is the mass of a mole of water. Would someone correct the Lapse rate accordingly? Thanks, mbeychok
where: | |
= Wet adiabatic lapse rate, K/m | |
= Earth's gravitational acceleration = 9.8076 m/s2 | |
= Heat of vaporization of water, J/kg | |
= The ratio of the mass of water vapor to the mass of dry air, kg/kg | |
= The universal gas constant = 8,314 J kmol-1 K-1 | |
= The molecular weight of any specific gas, kg/kmol = 28.964 for dry air and 18.015 for water vapor | |
= The specific gas constant of a gas, denoted as | |
= Specific gas constant of dry air = 287 J kg-1 K-1 | |
= Specific gas constant of water vapor = 462 J kg-1 K-1 | |
=The dimensionless ratio of the specific gas constant of dry air to the specific gas constant for water vapor = 0.6220 | |
= Temperature of the saturated air, K | |
= The specific heat of dry air at constant pressure, J kg-1 K-1 |
The derivation of the dry adiabatic lapse rate is not understandable since not all symbols are defined.I think that for an average reader the names of all symbols should be given. — Preceding unsigned comment added by FrankBerninger ( talk • contribs) 07:04, 19 October 2011 (UTC)
There are several paragraphs repeated under "Mathematical definition" that are already under "Definition". Jon Stephen Horridge ( talk) 12:08, 4 April 2012 (UTC)
Conversions should be provided for non-metric users. Aviation users in particular need to know feet/F rather than km/C for the dry adiabatic lapse rate.
UPDATE FOR PILOTS. In Europe we use the JAA as the aviation authority, and they state and test that the SALR is 0.6C/100m for the purpose of the ATPL exams. Very seldom do instructors and very seldom in the exams now will you see the SALR as c/ft. (1.8C/1000ft).-- Pugzi 08:29, 15 May 2006 (UTC) (Steve Francis)
British english calls this a slew rate rather than lapse rate. I found this article a little difficult to find due to different terminology. Are we able to put in a redirection?
Tony Wallace — Preceding unsigned comment added by 122.58.21.179 ( talk) 07:04, 22 June 2013 (UTC)
The formula given in the article is:
Substituting numerical values, this expands to:
The prefactor looks good since this is the same as the dry adiabatic lapse rate. However, when I run some numbers, the results don't look reasonable:
The article says that the moist adiabiatic lapse rate is typically around 5 °C/km, and many other sites on the internet seem to support that.
If I had to guess the problem is actually with that second dimensionless r, and the formula should be:
So that are squared together in the denominator. In that case, the numerical expansion is:
Which then gives:
However, guessing is not really a good solution. So could someone please try to verify / derive the formula to figure out what the correct expression is. Dragons flight ( talk) 20:21, 13 September 2013 (UTC)
The notation °C was recently (Nov. 16) changed to C° throughout. If this is standard for relative temperatures I'm happy to leave it as is, if not I'll either revert it or change it to K as people prefer. Vaughan Pratt ( talk) 23:33, 1 March 2015 (UTC)
It starts well enough - A formal definition from the Glossary of Meteorology is:
.... and then immediately degrades into fantasy
The atmosphere isn't "warmed by conduction..."; if it was, the temperature at a few metres above the surface would be very low. Air is a good insulator. Neither has lapse rate anything to do with "parcels of air".
The discussion for Dry adiabatic lapse rate contradicts itself immediately. After stating that
which is of course correct, and
which also is correct and contradicts the earlier "warmed by conduction...". it goes on to state
"loses internal energy" must mean loss of kinetic energy, which means that the process as described in this article is not adiabatic.
I've found similar descriptions on many (most?) university websites, all discussing "rising parcels of air", occasionally envisaging an "invisible container" which has "work done on it" by the "expanding air".
The lapse rate is a characteristic of Earth's atmosphere whether "parcels of air" rise, fall or dance a jig. Those imaginary "parcels" are expanding into an atmosphere whose temperature (in the troposphere) and pressure decrease with height; in other words, an existing set of conditions. This article doesn't address the reason(s) for those conditions, and so is fundamentally flawed. Rambler24 ( talk) 18:32, 1 March 2013 (UTC)
The relationship between temperature and pressure is nearly fixed (it'll vary as the composition of the atmosphere changes, but presumably not by much). However, the relationship between pressure and altitude is not so nearly fixed, since it depends on the density profile over altitude, which depends on temperature over altitude (and also on humidity over altitude, to some extent).
The relationship of temperature and pressure is
The here is not the same as the gamma used in the article body to denote lapse rate. The usage in the article is unfortunate, since is usually used to denote the specific heat ratio, see adiabatic. Is the article's usage standard?
The pressure in the atmosphere drops off approximately exponentially with altitude. This means a 1000m increase in elevation typically produces a 12.6% drop in pressure. That drop in pressure would cause a 3.45% drop in temperature, which is about 10 C.
In any case, my point is that pressure at altitude varies, and varies with some independence from the pressure at sea level directly below, and as a result the dry adiabatic lapse rate is not a constant.
Iain McClatchie 18:34, 1 October 2005 (UTC)
Ok, it's not strictly constant, but it does turn out to be vary remarkably little if you do the numerical integration.
Customarily, undergraduates are shown the simple derivation giving the dry lapse rate of -g K/km, or -9.86K/km. This at ground/sea level. Once water vapour is present the figure is 6.5K/km. The potential temp greatly increases with altitude, of course. 27.33.81.127 ( talk) 06:20, 1 February 2016 (UTC)
"For example, there can be an inversion layer in which the temperature increases with altitude."
I think I am correct in saying that the temperature does not necessarily need to increase in temperature to be described as an "inversion." If the lapse rate drop below the standard lapse rate this is also called an inversion because this is the boundary where major meterological behavior ceases because the air has no excess temperature derived kinetic energy and stops rising. (It may still have horizontal kinetic energy - wind.) Most atmospheric inversions are not strict inversions and this can be very confusing nomenclature for people when they see a measured lapse rate chart on a day "with an inversion" and there is no temperature reversal illustrated. I've done no editing but feel free to do so. Anyone who rewrites relevant sections should incorporate some of the above using filled in lapse rate charts as an illustrative tool. Ecstatist ( talk) 04:17, 2 December 2016 (UTC)
Please relate this to the article. Biggerj1 ( talk) 08:27, 26 June 2018 (UTC)