Air Masses and Fronts Lab

Problem: What happens when warm and cold air masses meet?

Background: A huge body of air that has similar temperature, humidity, and airpressure at any given height is called an air mass. Scientists classify air masses according to temperature and humidity. Four major types of air masses influence the weather in North America: maritime tropical, continental tropical, maritime polar, and continental polar. Tropical, or warm, air masses form in the tropics and have low air pressure. Polar, orcold, air masses form north of 50° north latitude and south of 50° south latitude and have high air pressure. Maritime air masses form over oceans and are humid. Continental air masses form over land and are dry.

Colliding air masses can form four types of fronts: cold fronts, warmfronts, stationary fronts, and occluded fronts. A cold front forms when coldair moves underneath warm air, forcing the warm air to rise. Cold fronts movequickly and bring cold, dry air. A warm front forms when warm air movesover cold air. Warm fronts move slowly and bring warm, humid air. Astationary front forms when cold and warm air masses meet but neither onehas enough force to move the other. It may bring many days of clouds andprecipitation. An occluded front forms when a warm air mass is caughtbetween two cooler air masses. The warm air mass is cut off, or occluded, fromthe ground. The occluded warm front may cause clouds and precipitation.

Hypothesis: If a warm and cold air mass meet,

then

a. they will mix together

b. the cold air mass will slide over the warm air mass

c. the warm air mass will slide over the cold air mass

because…

Experimental Design

Ind. Variable: temperature of water

Dep. Variable: behavior of water

Control: Room temperature water

Procedure

  1. Color water with ice blue
  2. Color heated water red.
  3. Form barrier
  4. Pour water on either side
  5. Remove barrier, observe from side

Materials

  1. Plastic container
  2. Red water
  3. Blue water
  4. Barrier
  5. Clay

Lab 1 – Different Densities

Before / After

Conclusion – Air masses and Fronts Lab 1

  1. Was your hypothesis correct? Why or why not?
  2. What does the blue water represent? …the red water?
  3. What would happen if we slowly remove the divider?
  4. What happens as the fluids are observed longer?

Lab 2 – Front Formation

Before / After

Conclusion – Lab 2

  1. Was your hypothesis correct? Why or why not?
  2. Why doesn’t the pepper rise through the top layer of water?
  3. What does the cold water represent?
  4. What does the boundary between the cold and warm water represent?