.. so to summerise... if a cloud has not formed use DALR of
3 deg/1000' as it is clear (dry) air under the cloudbase....
Cloubase calculations use DALR which is all you are likely to require at PPL level.
SALR and DALR are used to calculate cloud bases either side of a mountain ridge.. the Fohn effect.
In this case air uplifted by terrain cools at DALR until the dewpoint is reached ( cloudbase on the windward side) and thereafter cools at the SALR until the summit is reached.
Precipitation is assumed to have taken place, and the air on the leeward side has a higher dewpoint, which in turn gives a higher cloudbase as the air descends the lee slope cooling at the SALR.
This use to be a CAA favourite .. but that was a long tine ago !
Last edited by Teddy Robinson; 7th July 2004 at 23:37.