WW2010
University of Illinois

WW2010
 
  welcome
 
> online guides
 
  archives
 
  educational cd-rom
 
  current weather
 
  about ww2010
 
  index

Online Guides
 
  introduction
 
  meteorology
 
  remote sensing
 
> reading maps
 
  projects, activities

Reading Maps
 
  introduction
 
  utc conversions
 
  temp conversions
 
  surface obs
 
  surface maps
 
> upper air obs

Upper Air Obs
 
  overview
 
  temperature
 
> dew point
 
  height
 
  wind barbs
 
  300 winds & heights

User Interface
 
  graphics
> text

NOTE: We've guessed that you're not using a client that supports colored tables and have tried to compensate. Low graphics mode looks much better on clients that do... we recommend switching to Netscape 3.0 or Microsoft Internet Explorer.
.
Dew Point Temperature
upper air station reports

The value highlighted in yellow located in the lower left corner (in the diagram above) is the dew point temperature in degrees Celsius. In this example, the reported dew point temperature is 58 degrees.

Dew Point Temperature is defined as the temperature at which air would have to cool (at constant pressure and constant water vapor content) in order to reach saturation. Dew points provide insight into the amount of moisture in the air. The higher the dew point temperature, the higher the moisture content for air at a given temperature.

When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is NEVER GREATER than the air temperature. Therefore, if the air cools, moisture must be removed from the air and this is accomplished through condensation. This process results in the formation of tiny water droplets that can lead to the development of fog, frost, clouds, or even precipitation.

Other upper air observation maps may actually report dew point depression instead of dew point temperature. Dew point depression is the difference in degrees Celsius between the temperature and the dew point. In the example above the dew point depression would be 20 degrees.

What to Look For in Dew Point Observations:

  • Relative Humidity can be inferred from dew point values. When the air and dew point temperatures are very close, this indicates that the air has a high relative humidity. The opposite is true when there is a large difference between air and dew point temperatures, which points to air with a low relaitve humidity.



temperature
Terms for using data resources. CD-ROM available.
Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.

Height