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Old 27th February 2002 | 12:53
  #22 (permalink)  
bookworm
 
Joined: Aug 2000
Posts: 3,648
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From: UK
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Evo 7

It is a little confusing that MALR and ELR are presented in such a similar way in many texts.

The moist (or saturated) adiabatic lapse rate is, in effect, a law of physics. If you change the pressure of a parcel of air without allowing heat to flow in or out, the temperature will change by a predictable amount. It varies with the temperature you start from, but not from day to day.

The environmental lapse rate of 2 degC/1000 ft is a day-to-day 'average', which is also used to define the international standard atmosphere.

If you look at an . .<a href="http://weather.uwyo.edu/upperair/sounding.html" target="_blank">Atmospheric Sounding</a> you'll see that the real temperature profile of the atmosphere can be nothing like the smooth 2 degC/1000 ft average. It's a jaggy line that goes all over the place.

The shape of the real environmental lapse rate, not the day-to-day average, determines the stability of the atmosphere and the convective cloud bases and tops.

Hope that helps.
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