Virtual Science Teachers
Weather Fronts: Interactive Cold and Warm Front Simulation

Weather Fronts

How cold fronts and warm fronts change the weather

How to explore

  1. Pick a front type: Cold Front or Warm Front.
  2. Set the warm air humidity slider. This is the moisture in the rising warm air.
  3. Press Play, or drag the Time slider yourself.
  4. Watch the stick person and read their weather report below the picture. What happens before, during, and after the front passes?
Tip: the space bar plays and pauses.
Warm air humidity Dry Humid 70% (humid)
Time Hour 0 of 6
Cold Front Warm air Cold air Cold front Rising warm air Cumulonimbus Nimbostratus Altostratus Cirrostratus Cirrus Virga: rain evaporating in dry air Front movement Hour 0 of 6

Weather report where the stick person is standing

Front status…
Sky…
Precipitation…
Temperature…
Wind…
Air pressure…
Science notes: why does the humidity slider control the warm air?
  • Clouds come from rising warm air. At a front, the warm air is the air pushed upward. Rising air cools, and its water vapor condenses into clouds. That is why the slider controls the warm air's humidity.
  • More humidity = thicker clouds and more rain. Humid warm air builds low, thick clouds with heavy or steady rain. At a cold front, very humid air can build a thunderstorm.
  • Less humidity = thinner clouds and less rain. In dry air, falling raindrops can dry up before they reach the ground. Those fading streaks of rain are called virga.