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

Meteorology
 
  introduction
 
  air masses, fronts
 
  clouds, precipitation
 
  el nino
 
> forces, winds
 
  hurricanes
 
  hydrologic cycle
 
  light, optics
 
  midlatitude cyclones
 
  severe storms
 
  weather forecasting

Forces, Winds
 
  introduction
 
  pressure
 
  pressure gradient
 
  coriolis force
 
  geostrophic wind
 
  gradient wind
 
  friction
 
  boundary layer wind
 
  sea breezes
 
> land breezes

Land Breezes
 
  low-level cooling
 
> onshore flow aloft
 
  circulation

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.
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Onshore Flow Aloft
precursor to the land breeze at the surface

Since warm air is less dense than cool air, the air over land contracts in response to radiational cooling from the ground below. This contraction leads to a decrease in the distance, or "thickness", between constant pressure surfaces within the cooled air. Over water, where the air cools much more slowly, such contraction does not occur and the distance between pressure surfaces remains about the same.

In response to additional cooling, an area of low pressure (red "L") develops at higher levels over land while an area of high pressure (blue "H") develops over water.

The resulting pressure gradient force causes air at higher levels to flow onshore (from high to low pressure).



low-level cooling
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.

circulation