Greetings from Co Durham (Trimdon, 130m asl).

We spend a week most years XC Skiing in Arctic Lapland. Not Jack London stuff, a civilised package tour but it means I've been out regularly in really cold weather, -30 this year.

Meto keeps giving us "feels like" temps with wind chill. Well it doesn't. Leaving aside somewhat better clothing (actually not hugely better) it stikes me that the current wind chill figures are just plain wrong. Yesterday in Tesco's car park* felt a heap worse than wandering about at -15 in still air.

Who calculates these figures? On what basis? Comfort wise they just feel wrong.

Andrew

*That really was Call of the Wild BTW

On Monday, March 25, 2013 7:19:46 AM UTC, wrote:
Greetings from Co Durham (Trimdon, 130m asl).



We spend a week most years XC Skiing in Arctic Lapland. Not Jack London stuff, a civilised package tour but it means I've been out regularly in really cold weather, -30 this year.



Meto keeps giving us "feels like" temps with wind chill. Well it doesn't.. Leaving aside somewhat better clothing (actually not hugely better) it stikes me that the current wind chill figures are just plain wrong. Yesterday in Tesco's car park* felt a heap worse than wandering about at -15 in still air.



Who calculates these figures? On what basis? Comfort wise they just feel wrong.



Andrew



*That really was Call of the Wild BTW

http://www.crh.noaa.gov/ddc/?n=windchill

Yes, I have often wondered about the usefulness of wind-chill figures in general public forecasts.

For mountain and maritime forecasts, where people are going to be exposed to strong winds and low temperatures for long periods - fine.

But for the average person walking to the shops, does putting a figure on the wind-chill effect actually achieve anything, apart from pandering to exaggerated headline writers?

One curious thing which as always confused me, is why the w-c calculator takes no account of the humidity of the air. I think most people would agree that a 20 mph wind and an air temperature of minus 1 will feel different if the dew point is either minus 1, or minus 10.

wrote:

Greetings from Co Durham (Trimdon, 130m asl).

We spend a week most years XC Skiing in Arctic Lapland. Not
Jack London stuff, a civilised package tour but it means
I've been out regularly in really cold weather, -30 this year.

Meto keeps giving us "feels like" temps with wind chill. Well
it doesn't. Leaving aside somewhat better clothing (actually
not hugely better) it stikes me that the current wind chill
figures are just plain wrong. Yesterday in Tesco's car park*
felt a heap worse than wandering about at -15 in still air.

Who calculates these figures? On what basis? Comfort wise
they just feel wrong.

I've also spent a considerable amount of time in the frozen north, and
agree with your perceived cold observations. AFAIK, no wind chill
calculation formulas take account of air humidity. In inland arctic
areas, typical air humidity levels can be 30-50% on cold winter days,
whereas the last couple of days[1] I looked up and saw online figures[2]
for midland locations between 90-100% RH.

In a draft of cold air saturated with H2O, I'd guess that water droplets
may form, and on contact with naked skin draw heat to evaporate.

Even if you spent some time outdoors in your Tesco car park, you
probably wont suffer from dried out skin (lips) - which is very common
in the dry and cold air of the arctic. Thats why the Nivea skin
moisturiser range is commonly available and much used there.

[1] after feeling very cold in a Morrisons (!) car park
[2] http://weather.noaa.gov/weather/GB_cc.html

--
ts // scrap vehicle to send e-mail

"willie eckerslike" wrote in message
...
Yes, I have often wondered about the usefulness of wind-chill figures in
general public forecasts.

snip

One curious thing which as always confused me, is why the w-c calculator
takes no account of the humidity of the air. I think most people would
agree that a 20 mph wind and an air temperature of minus 1 will feel
different if the dew point is either minus 1, or minus 10.

The Met Office "feels like" temperatures _do_ take into account humidity.

Meto keeps giving us "feels like" temps with wind chill.

AFAIK, no wind chill calculation formulas take account of air humidity.

Met Office "feels like" temperature forecasts use a formula that takes into
account humidity. I don't know what the formula they use is (you could ask
them), but such formulae do exist - here's one from the Australian
meteorology bureau -
http://www.bom.gov.au/info/thermal_s...tapproximation

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx for hourly reports

Freddie wrote:

Meto keeps giving us "feels like" temps with wind chill.

AFAIK, no wind chill calculation formulas take account of air humidity.

. . . such formulae do exist - here's one from the Australian
meteorology bureau -
http://www.bom.gov.au/info/thermal_s...tapproximation

Ah, yes - for hot climates, to help fighting heat stress. That't why the
site is an Australian one :-)

That website also reproduced a chart for sub-zero temperatures, with
"wind chill temp" as a function of temperature and wind speed, but with
a _fixed_ RH of 70 %.

What I meant to say was "AFAIK, no wind chill calculation formulas take
account of air humidity for sub-zero temperatures."

--
ts // scrap vehicle to send e-mail

On Monday, March 25, 2013 10:06:21 AM UTC, Freddie wrote:
Meto keeps giving us "feels like" temps with wind chill.



AFAIK, no wind chill calculation formulas take account of air humidity.



Met Office "feels like" temperature forecasts use a formula that takes into

account humidity. I don't know what the formula they use is (you could ask

them), but such formulae do exist - here's one from the Australian

meteorology bureau -

http://www.bom.gov.au/info/thermal_s...tapproximation



Goodness gracious. All that effort for a figure that means very little to the average punter?

On Mon, 25 Mar 2013 10:36:37 +0000,
(ts) wrote:
What I meant to say was "AFAIK, no wind chill calculation formulas
take
account of air humidity for sub-zero temperatures."

But they do exist - the Met Office use one for their "feels like"
temperatures. Ask them if you want to know details.

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx for hourly reports

On Mon, 25 Mar 2013 04:00:35 -0700 (PDT), willie eckerslike
wrote:
Goodness gracious. All that effort for a figure that means very
little to the average punter?

So make the effort and learn. Google is your friend.

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx for hourly reports