Knowing what the dew point is ...

[AlistairHowie]

I used to be a private pilot and it occurred to me that weather information regularly made available to pilots would be of use to amateur astronomers, since it contains information on the dew point.

Each airport around the world issues what are called METARs, usually at 10 minutes and 50 minutes past each hour. They report current weather conditions and are presented in standard format. At first sight they can look confusing, but they are easily interpreted with practice and there are many websites about which will automatically translate their contents for you.

For example, the METAR for my local airport (Luton) from here UKww METAER DEcoder is as follows ...

2011/12/28 10:20 EGGW 281020Z 25016KT 9999 BKN019 09/06 Q1018

That same website will also translate it for you:

Location: Luton Airport

ICAO Code: EGGW

Day of month: 28

Time: 10:20 UTC

Wind: True direction = 250 degrees, Speed: 16 knots

Visibility: 10 km or more

Clouds: Broken sky , at 1900 feet above aerodrome level

Temperature: 09 °C

Dewpoint: 06 °C

QNH (Sea-level pressure): 1018 mb

You don't actually need to understand any of it, except the two numbers separated by a slash near the end of the line .... 09/06 in this case.

This shows the current temperature is 9 degrees C and the dew point is 6 degrees ... so quite close to each other. And as you know, when the temperature drops to dew point, mist, fog, dew, frost etc can occur.

Hope this is of use.

Cheers.

[dweller25]

Thanks for that Alastair.

Sometimes (actually quite a lot in the UK) the temp and dewpoint will show M01/M03 for minus figures.

[tony]

I used to be a private pilot and it occurred to me that weather information regularly made available to pilots would be of use to amateur astronomers, since it contains information on the dew point.

Each airport around the world issues what are called METARs, usually at 10 minutes and 50 minutes past each hour. They report current weather conditions and are presented in standard format. At first sight they can look confusing, but they are easily interpreted with practice and there are many websites about which will automatically translate their contents for you.

For example, the METAR for my local airport (Luton) from here UKww METAER DEcoder is as follows ...

2011/12/28 10:20 EGGW 281020Z 25016KT 9999 BKN019 09/06 Q1018

That same website will also translate it for you:

Location: Luton Airport

ICAO Code: EGGW

Day of month: 28

Time: 10:20 UTC

Wind: True direction = 250 degrees, Speed: 16 knots

Visibility: 10 km or more

Clouds: Broken sky , at 1900 feet above aerodrome level

Temperature: 09 °C

Dewpoint: 06 °C

QNH (Sea-level pressure): 1018 mb

You don't actually need to understand any of it, except the two numbers separated by a slash near the end of the line .... 09/06 in this case.

This shows the current temperature is 9 degrees C and the dew point is 6 degrees ... so quite close to each other. And as you know, when the temperature drops to dew point, mist, fog, dew, frost etc can occur.

Hope this is of use.

Cheers.

i never knew that. very useful info, cheers.