Relationship between height and wind speed

[xmetman]

Just out of interest I decided to plot the wind speed for both mean speed and maximum gusts against height for the last 36 hours for the UK to see if I could see the relationship between wind speed and height.

There are clearly not enough AWS reports above 300 metres across the country to make these results more accurate.

I really should have selected the sites more carefully because winds across southern areas were much lighter.

If I had the info in my stations table I could have also plotted coastal sites in a different colour to differentiate them from inland stations but I don't.

These are the results for mean speeds.

These are the results for maximum gusts (ignore the labels).

[Jack Harrison]

Ah, but that is presumably not in free air.  The very high wind over top of Cairngorm would have been greater than in the free air at that height due to the squeeze.

Also, surface winds can be extraordinarily high locally due to the mountain wave effect.  I once foolishly "landed" my glider (that word "landed" is a minor exaggeration) by the airfield which was under the trough of the wave system.  More sensible pilots opted to land in fields half a wavelength further downwind (under the crest where the winds were much lighter) and reported gentle conditions.  Occasionally the surface wind can even reverse direction under the crest of the wave.

Incidentally, I damaged my glider but it was repairable.

Similar wind effects can occur in most mountainous area.  
I recall one landing I made (BAe 146 passenger aircraft) at Innsbruck where in Foehn conditions there was a tail wind at each runway threshold.

Incidentally, I didn't damage the airliner!

Jack

[xmetman]

I've seen the reverse wind at Kinloss under a rotor on a number of occasions. The bar cloud if there is one is stationary, always forming and dispersing. Usually there's a light sea breeze from the north and a strong southerly aloft. Eventually the southerly will win out. We did have a mobile boundary layer system at Kinloss but I don't think anyone launched it to investigate the wind and temperature structure.

[Freddie]

If I had been there I would have!

--
Freddie
Ystrad Rhondda

[xmetman]

This is the classic event that I was thinking of on 1 May 1990.

I'm sure it wasn't till later that we got the Vaisala BLS system.

[quaesoveritas]

I have never understood why the MO forecasted wind speeds for Whitley Bay tend to be higher than those for Albemarle, the nearest MO observation site, when the latter is 146m above sea level and Whitley Bay is only at 19m.

That would suggest that the MO think that wind speed reduces as altitude increases.

However, my own observed speeds at WB are nearly always considerably lower than the MO forecasts.

[Freddie]

The weather model orography isn't an exact replica of the real-life orography.  Maybe there is some high ground near Whitley Bay that the model has insufficiently "smoothed" such that the data point at Whitley Bay is at a greater elevation than in reality?  Or maybe there is real-life orography that has an effect on the immediate Whitley Bay climate that isn't properly resolved by the model?

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind measurement currently)

[Freddie]

On Sunday, 17 June 2018 08:43:16 UTC+1, xmetman wrote:

This is the classic event that I was thinking of on 1 May 1990.

I'm sure it wasn't till later that we got the Vaisala BLS system.

Yes, I remember that event well.  I was at Brawdy at the time - about the only time we got high temperatures there was in a reasonably strong (but not too strong) southeasterly.

[Freddie]

On Sunday, 17 June 2018 10:46:20 UTC+1, Freddie wrote:

On Sunday, 17 June 2018 08:43:16 UTC+1, xmetman wrote:

This is the classic event that I was thinking of on 1 May 1990.

I'm sure it wasn't till later that we got the Vaisala BLS system.

Yes, I remember that event well.  I was at Brawdy at the time - about the only time we got high temperatures there was in a reasonably strong (but not too strong) southeasterly.

I think the boundary layer sondes came along four or five years later.  We had one at Shawbury at the end of the 90s, and I was always very keen to use it to further investigate local effects.

[xmetman]

I seem to remember that we kept one balloon tethered for an afternoon at 30 feet on a weekend shift to use like an old BALTHAM.

[Freddie]

I always wanted to do something like that when we were fogged out, but couldn't get approval :-(

--
Freddie
Ystrad Rhondda

[quaesoveritas]

AFAIK there is no high ground near Whitley Bay, although I don't really know what the precise location is for the forecast.

To be fair, I don't live actually on the coast, but I wouldn't have thought that the forecasted speeds would be higher there.

I have noticed that actual wind speeds can vary enormously depending on the direction of the wind and which way your street faces.

[Metman2012]

Ahh balloons. When I was first at Kew Observatory there was an old barrage balloon there which was used for slant visibility research (when it was foggy). Considering that the Observatory was on the approach to 28L (now 27L) and the planes would be at about 1300 ft up at that point and the prevailing wind is SWly, I'm surprised it was allowed. There were instructions about what to do if it escaped. However, it then deflated and was taken away not to be replaced. We had hydrogen cylinders for pilot balloons - I think we did an occasional one. But then they decided to build a mini balloon shed, rubber floor and all. The day it was finished the hydrogen cylinders were taken away never to be replaced.

[xmetman]

Hydrogen was quite dangerous. 

The only time I did fill any pilot balloons was to pass some time on sunny afternoons at Andover waiting for the planes to return.