From: cohler@vxcrna.cern.ch (Mike Cohler)
Subject: Re: Hunting for thermals.
News-Software: VAX/VMS VNEWS 1.41    
Organization: European Organization for Nuclear Research, CERN
Date: Fri, 2 Oct 1992 08:51:00 GMT

In article <10504@uqcspe.cs.uq.oz.au>, colin@cs.uq.oz.au writes...
>Hello to r.a.s!
> 
>I'd like to start a discussion on how people hunt for thermals. Here in
>Oz I'm spoiled rotten, but I'm returning to the UK in the
;lines deleted
>interesting). I'm obviously interested in any UK-specific techniques.  
> 
You seem to have listed the techniques I use here in the UK also. The other
important thing that I recommend is learning which cumulus clouds have 'died'
and which are still alive !!  Clouds which are crisp and white at the tops
and good grey nearly level bottoms are usually working well, whilst those
which are not well defined at the tops, and showing furry looking bottoms
are often running out of lift.   Sometimes near cloudbase you may find
a 'step' in the cloud... ther is often excellent lift up the side of the
'step.   Watch out for mammatus.. globs of cloud hangind down from a big
cloud... these indicate sink.     As for sources of thermals.... in the UK
we use a variety of indicators... towns, brown fields... rape fields.....
power stations.... stubble fires (though they are bow banned !)... runways...
rubbish tips( Often produce thermals even in winter !).

  Of course our British thermals are often now anywhere as strong as those
which you may have experienced in Oz.  Here we often get days in summer ]
where 'scratching' in 1 to 2 knot thermals is the norm.  I did my silver 
distance on a day when the first 40 km were in thermals no stronger than 
3 knots !!    On a "superb" day we get 6 or even 8 knots, and once a year
you get a '10 knotter'.   One of my colleagues went to the USA recently
and took a glider flight (dual).  He started thermalling in a 3 knot thermal.
This prompted the instructor to comment " What the hell are you doing ?"
"Thermalling".... Nah, here in this part of the states we forget any
thermal less than 6 knots"   ... !!
     Also look for cloud "streets"... at times I have had continuous
3 knots of lift under a street, at an air speed of 70 knots in a K6,
for about 6 miles, without even the need to make a turn.  
     "Local knowledge" is important in the UK.. when you come here seek 
out the local "thermal guru" where you will be flying, and you will learn
a lot.   Also a fair number of clubs here are "ridge" sites, where there
is continuous lift along a ridge of hills, and on the sun facing slopes
of ridges, there are often very good thermals almost continuously generated.
     There is a lot to learn !!
     I am sure more experienced pilots than I will add to this discussion.
Mike

==============================================================
|                                                            |
|        Mike Cohler -  preferred email address:             |
|                       MDC1@VAXA.YORK.AC.UK                 |
|                   ie  MDC1%VAXA.YORK.AC.UK@UKACRL.BITNET   |
|                                                            |
|        UK PPL and Glider Pilot                             |
|                                                            |
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