On Thu, 5 Feb 2004 09:14:31 -0000, Julian Scarfe wrote in


So far so good, but I don't think it tallies with reality. The pilot's
rule-of-thumb is that the wind at altitude veers 30 degrees and doubles in
strength. It varies but that's not unusual. It's not uncommon to see
doubling or tripling of wind speed as you cross the boundary layer, but veer
angles don't often exceed 30 degrees. A 60 degree veer seems very unusual.

But according to the formula above, a ratio of 50% should be associated with
a 60 degree veer, or putting it the other way round a 30 degree veer should
be associated with a much smaller increase in wind speed.

So where does the model above break down?

As John Whitby suggests, stability may well be a factor, but is not built
into that simple model. Another factor, related I think, is the model,
being so simple, is probably based on laminar flow theory - to make
understanding easier. Introduce turbulent flow, which we have to in the
real atmosphere to varying degrees, and the simplicity of that model is
seen to introduce errors when it comes to making any calculations.

--
Mike 55.13°N 6.69°W Coleraine posted to uk.sci.weather 05/02/2004 13:21:41 UTC