Tom’s post got me to thinking about the other weather measurement that I don’t understand… the Dew Point. Luckily there is a world wide web of information (a super highway, if you will) that can explain these mysteries.

The Dew Point (or dewpoint) is the temperature which air must be cooled to in order for the water vapor in the air to condense into water (dew).

Dew Points are related to relative humidity.

From Meteorologist Steve Horstmeyer:

In terms of relative humidity, as the parcel of air is cooled, the relative humidity increases, when the relative humidity reaches 100%, the air parcel has cooled to the dew point temperature. At a relative humidity of 100% the dew point temperature ALWAYS equals the temperature. The greater the difference between temperature and dew point the lower the relative humidity.

Generally, the higher the Dew Point, the higher the relative humidity, and the more uncomfortable you will feel.

But next time you’re hot, remember, it could be worse:

The highest recorded dew point was 35°C (95°F), reported in Dhahran, Saudi Arabia at 3 p.m. July 8, 2003. The temperature was 42.2°C (108°F) resulting in an apparent temperature or Heat Index of 77.7°C (172°F).

172!!!!!!!!!!!!!!!!!!!!!!!!!!

Source: Mr. Horstmeyer, and wikipedia with the assist.