Lesson 4: Clouds and Fog
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Precipitation Type (more on Figure 6-22)

Use this applet to explore how the temperature and moisture (represented by the wet-bulb temperature) below the cloud base determine the type of precipitation that reaches the ground. You might want to review concepts of wet bulb temperature before exploring this applet.

Some questions to consider:

  • Can you have snow reaching the surface if the temperature near the surface is above freezing?
  • Why does the air temperature cool to the web-bulb temperature? What is the relative humidity when they are equal?
  • If the temperature below the cloud is much larger than the wet-bulb temperature, what happens to the precipitation?
  • Have you ever observed a snowfall when the surface temperature is above freezing?

    Set the temperatures and wet bulb temperatures by dragging the points and learn what type of precipitation will fall to the ground. Each time you release the mouse button, the simulation starts. (And try to see what influence an updraft in the cloud has on precipitation.)