What is the difference between ambient temperature of minus 15 Deg. Centigrade and dew point of minus 15 Deg C

Question

Both units of temperature measured in centigrade, we can feel the ambient temperature of minus 15 Centigrade being very very cold, where as we can feel dew point temperature of minus 15 Deg. Centigrade of air are not of much cold?

Answer 1

Dew point is nothing more than the temperature at which water condenses. For instance, if the dew point and temperature is within three degrees you will get fog.

Answer 2

As stated in previous answers, the dew point is the temperature at which water will condense. That is it will go from the vapor phase to the liquid phase.

Another way to look at Dew Point is, it is a measure of water content in the air. On a very humid day just before it begins to rain, the dew point will be approaching the ambient temperature. Even on very hot days. This means that the amount of water vapor in the air very high. On the other hand the dew point can be very low...even less than zero degrees Centigrade. This would mean that the moisture content of the air was very low. A good example of low water water content in the air, meaning a low dew point temperature would be the inside of a refrigerator. While the temperature is cold, the water content is even lower so no moisture appears.

In a single sentence dewpoint tells you how much water is in the air, and temperature tells you how warm it is.

Answer 3

As previously said. temperature and dew point are two different things.
Dew point is the temperature at which humidity (water vapour) in the air condenses.
It is a couple of parameters pilots watch carefully on met forecasts: if the air is at 25C at sea level and dew point very close to this, the cloud ceiling is going to be close to the ground, and flying in clouds is no fun.
Using the dew point and ground temperature, we can estimate at what level we will encounter the clouds' base: 1 degC, 500 feet, 2 decC, 1000 feet (500 feet per deg C difference).
We cas also derive the dew point by looking at the cloud's base doing the reverse operation!
(This is not totally exact, air pressure, density and so on enter in consideration as well, but it's a good rule of thumb.)