FRONTS FRONTS

CQ# 41: What happens when two air masses meet? Answer Front- The area where two air masses meet and do not mix. From military language meaning a battle area where opposing armies meet to fight

Cold Front A cold air mass runs into a slowly moving warm air mass, the denser cold air slides under the lighter warm air. The warm air is pushed upwards.

What will happen if the warm air mass contains only a little water vapor? Warm air with little water vapor may be accompanied by ONLY cloudy skies. If there is a lot of water vapor in the warm air, heavy rain(thunderstorms)or snow may fall.

After a cold front passes Skies clear up and leaves cooler temperatures.

Warm Fronts At a warm front, moving warm air collides with a cold air mass. Cold air is more dense than warm air, so the warm air moves over the cold air.

What type of weather do we see with a warm front ? If warm air is humid, showers and rain fall along the front. In winter warm fronts can bring snow. If warm air is dry, scattered clouds form. Because warm fronts move more slowly, weather may be more foggy or rainy for several days. After a warm front passes, the weather is likely to be warm and humid.

Stationary Fronts Where cold and air masses meet, but neither has the force to move the other.

Weather along a stationary front Water vapor in the warm air condenses into rain, snow or clouds. Depending on wind direction front will start moving again becoming either a warm or cold front.

Occluded Fronts A cold front follows right behind a warm front. So a warm air mass pushes into a cold air mass, and then a cold air mass pushes into a warm air mass. The warm air rises as the two cold air masses come together. The cold front usually overtakes the warm air. Temperature air near the ground becomes cooler, and weather may turn cloudy, rainy or snowy.

Checkpoint: 1. What is a front? 2. What type of front is formed when moving warm air collides with a cold air mass? 3. What type of front is formed when a cold moving air mass collides with a warm air mass. 4.What type of front forms when two air masses meet and neither one can move? 5. Why do most fronts cause changeable weather, rain or cloud formation? 6. Why is the warmer air mass always pushed upward?