20th Jun 2000, 15:00
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#4 (permalink)
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Join Date: Aug 1998
Location: Ex-pat Aussie in the UK
Posts: 2,703
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Quote:
Air will cool at the DALR (Dry Adiabatic Lapse Rate) until it reaches the LCL (Lifted Condensation Level), and then from that point, it will cool at the SALR (Saturated Adiabatic Lapse Rate.)
However, this path changes as heat and moisture at the surface changes. As heat and/or moisture at the surface increases, the air parcel line is “shifted” to the right. The LCL also changes as heat and moisture changes. Both of these points are critical – we need to know,[list=a][*]by how much is the theoretical air parcel plot shifted to the right? And[*]where is the new LCL?[/list=a]
The relationship can be related by “Normands Theorem.” This simply states that the LCL is where the following lines intersect:- The DP (Dew Point) from 1000mb, taken up through the atmosphere following the pattern of a mixing ratio line.
- The Tw (Temperature of the wet bulb) from 1000mb, taken up through the atmosphere following the pattern of a SALR line.
- The T (Temperature) at 1000mb, taken up through the atmosphere following the pattern of a DALR line.
Where these three intersect, is where the LCL will lie.
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from: The Brisbane Storm Chasers Page
[This message has been edited by Checkboard (edited 20 June 2000).]
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Normands Theorem - Anyone got a web link ?
