Humidity & Barometric readings

[kingoftheworld]

Hi Guys,

First of all I wish everybody a really great X-mas & a succesfull fun 2008.

So down to Junior basics I'm 241m above sea level & it's currently -4.3 out there in freezing Vienna. I am really suprised by my VP showing 92% humidity! Now I really am a rookie & I am sure that there is a good reason for that so could someone
please explain what or guide me to a site thanks .

Simon

[Holli]

Sorry, no english explanation found: http://de.wikipedia.org/wiki/H-x-Diagramm

[Emma-Nina]

Hi,
here is a link leading to an English-version explanation.
Sounds rather complicated.At least for me.

http://en.wikipedia.org/wiki/Psychrometric_chart
Best Regards,
           Emma-Nina.

[kingoftheworld]

Thanks for you support Guys & Girls

I mean its clear for me why in warm temperatures there would be a high humidity, coastal areas, Citys surrounded by water (Singapore) etc.But minus 4, Vienna  & at 93% ? .

I was just wondering if I had calibrated something wrong with my vantage pro or is that a normal humidity ?

Thanks ..

[Emma-Nina]

Hi Simon,
that high humidity is pretty normal.Even in a city not surrounded by large areas of water.
Currently we have 93% rh in Berlin Tegel-Airport.
There's nothing wrong with your Vantage Pro-readings.
Perhaps it's the inversion weather-situation that leads to this high readings. Warm temperatures in higher regions lasting on cold air on the ground.
That could be the clue to it.
Best Regards,
           Emma-Nina.

[jusch]

I mean its clear for me why in warm temperatures there would be a high humidity, coastal areas, Citys surrounded by water (Singapore) etc.But minus 4, Vienna & at 93% ? .

I was just wondering if I had calibrated something wrong with my vantage pro or is that a normal humidity ?

That's rather normal during the cold months of the year.

Please be aware that "humidity in percent" always means "relative humidity". That is humidity relative to the saturated humidity.

Warm air can hold much more "absolute" vaporated water in it than cold air can.

Hava a look at http://upload.wikimedia.org/wikipedia/en/4/41/Relative_Humidity.png

While air at 30°C can hold about 27 grams of water in 1 kilogram of air (100% humidity at 30°C), the same 1 kilogram of air can hold only about 4 grams of water at 0°C (100% humidity at 0°C).

So 90% humidity at 30°C means, that there is an absolute of 0.9*27 = 24.3 grams water in the air, and 90% humidity at 0°C means, that there is only 0.9*4 = 3.6 grams of water in one kilogram of air.

[kingoftheworld]

Thanks Emma & Jusch,

Now I'm with it  

I was always trying to compare in my head the summer humidity levels & sort of try to match it to the Winter Months  

All clear

Have a nice one, 6kg bird here ready to be cooked on Christmas day.