On Wed, 01 Mar 2006 18:22:11 GMT, Jose
wrote in : :

A close temperature/dewpoint spread (less than 5 degree Celsius difference
between the two) can indicate the presence or possibility of fog.

Also, knowing the temperature and dew point one can estimate the cloud
bases (using a standard lapse rate of 2 deg/1000 feet).

The Relative Humidity, of which due point and temperature are an
indicator, is useful in predicting induction system icing in
carbureted engines.


http://www.lycoming.textron.com/main...tionIcing.html
Every pilot who flies an aircraft powered by a carbureted engine
should be thoroughly educated about carburetor ice. They should
know that under moist conditions (a relative humidity of 50% to
60% is moist enough), carburetor ice can form with any outside air
temperature from 20o to 90oF. It is most likely in the 30o to 60oF
range. Temperatures in the carburetor can drop 60o to 70oF
(refrigerator effect) as a result of fuel vaporization and the
carburetor venturi effect. It also happens that carburetor ice
forms more readily when the engine is operated in the lower power
range. It will form while taxiing and this makes it very important
to check engine power before takeoff and to remove the ice if
necessary. Care should be taken to avoid dusty or dirty conditions
when utilizing carburetor heat on the ground.