Weather Fronts
By Cindy Grigg

boundary	meet	northward
large	maritime	nimbostratus
stationary	forms	several
counterclockwise	huge	meets
between	center	anticyclones
form	cumulonimbus

Directions: Fill in each blank with the word that best completes the reading comprehension.

     Air masses are very (1)  _______________________   "pockets" of air. Often these (2)  _______________________   air masses cover ten thousand or more square miles. No air mass stays still for more than a few days at a time. They are always on the move. Their movements bring us changes in the weather.
     Air masses are named for where they form. They are usually called polar, arctic, tropical, or equatorial. Maritime air masses form over oceans. They usually carry a lot of moisture. Continental air masses form over land. They usually have drier air.
     Air masses are different in many ways. They have different temperatures. They have different atmospheric pressures and different moisture contents. Their patterns of movement are different.
     An air mass that (3)  _______________________   over land near the arctic would be called a continental arctic air mass. It would have cold, dry air. It would have high pressure. A (4)  _______________________   polar air mass would have cold, moist air. It would probably bring fog and drizzle as it moved into an area.
     Maritime tropical air masses (5)  _______________________   over warm ocean waters in the tropics and the Gulf of Mexico. They bring warm, moist air (6)  _______________________   into the United States. These would have low pressure. They may bring rain.
     Low pressure air masses are called cyclones. In a cyclone, the air moves in a (7)  _______________________   way towards the center of the mass.
     High pressure air masses are called (8)  _______________________  . In them, the air moves in a clockwise direction out from the (9)  _______________________  .
     When two air masses meet, the weather changes. The edge (10)  _______________________   the two is called a front. Each different kind of front causes a different kind of weather.
     A cold front is when a cold air mass pushes into a warm air mass. The heavier cold air sinks and slides in under the warm air. The cold air forces the warm air steeply upward along the front. This causes cumulus and (11)  _______________________   clouds to form. Rainstorms or thunderstorms usually develop. After the cold air mass passes, the rain stops. Dry, clear cool or cold weather follows.
     A warm front is when a warm air mass pushes into a cold air mass. Warm air is less dense than cold air. The lighter warm air slides up and over the cold air. High cirrus clouds form first as rising water vapor condenses. Later, (12)  _______________________   clouds may form and cause rain or snow.
     A (13)  _______________________   front happens when a cold front or a warm front stays in place for (14)  _______________________   days without invading another front. Clouds, light winds, and precipitation often form at the (15)  _______________________  . The precipitation may last for several days.
     An occluded front develops when two masses of cold air (16)  _______________________  . The cold air forces warmer air caught between the two fronts upwards. Cumulonimbus and stratocumulus clouds usually form. Strong winds and heavy rain or snow may result.
     Why do you think precipitation usually happens along a front? In most fronts, warm air (17)  _______________________   cooler air. As warmer air cools, it can hold less water. That's why some form of precipitation usually occurs.

Name _____________________________

Date ___________________

1.	What are air masses?

2.	Air masses are named for ______. Where they form People The type of air they contain Animals

3.	Low pressure air masses are called ______. Anticyclones Occluded front Stationary front Cyclones

4.	A cold front usually brings what kind of weather? Cool and dry Snow Rain and/or thunderstorms Sunny and fair

5.	When a cold front or a warm front stays in place for several days without invading another front, it is called a ______. Stationary front Warm front Cold front Occluded front

6.	When two air masses meet, what happens?

7.	Warm air is ______. Less dense than cold air Lighter than cold air Thinner than cold air All of the above

8.	When a warm and a cold air mass meet, what happens? The warm air would slide up and over the cold air. The heavier cold air would sink and slide in under the warm air. Some form of precipitation would occur. All of the above

9.	Cooler air can hold less water than warm air. False True

10.	Air masses are different in many ways. Which of these is not different? Temperature Moisture contents Atmospheric pressure Ratio of oxygen/nitrogen

Weather Fronts
By Cindy Grigg

Answer Key

     Air masses are very (1)  large   "pockets" of air. Often these (2)  huge   air masses cover ten thousand or more square miles. No air mass stays still for more than a few days at a time. They are always on the move. Their movements bring us changes in the weather.
     Air masses are named for where they form. They are usually called polar, arctic, tropical, or equatorial. Maritime air masses form over oceans. They usually carry a lot of moisture. Continental air masses form over land. They usually have drier air.
     Air masses are different in many ways. They have different temperatures. They have different atmospheric pressures and different moisture contents. Their patterns of movement are different.
     An air mass that (3)  forms   over land near the arctic would be called a continental arctic air mass. It would have cold, dry air. It would have high pressure. A (4)  maritime   polar air mass would have cold, moist air. It would probably bring fog and drizzle as it moved into an area.
     Maritime tropical air masses (5)  form   over warm ocean waters in the tropics and the Gulf of Mexico. They bring warm, moist air (6)  northward   into the United States. These would have low pressure. They may bring rain.
     Low pressure air masses are called cyclones. In a cyclone, the air moves in a (7)  counterclockwise   way towards the center of the mass.
     High pressure air masses are called (8)  anticyclones  . In them, the air moves in a clockwise direction out from the (9)  center  .
     When two air masses meet, the weather changes. The edge (10)  between   the two is called a front. Each different kind of front causes a different kind of weather.
     A cold front is when a cold air mass pushes into a warm air mass. The heavier cold air sinks and slides in under the warm air. The cold air forces the warm air steeply upward along the front. This causes cumulus and (11)  cumulonimbus   clouds to form. Rainstorms or thunderstorms usually develop. After the cold air mass passes, the rain stops. Dry, clear cool or cold weather follows.
     A warm front is when a warm air mass pushes into a cold air mass. Warm air is less dense than cold air. The lighter warm air slides up and over the cold air. High cirrus clouds form first as rising water vapor condenses. Later, (12)  nimbostratus   clouds may form and cause rain or snow.
     A (13)  stationary   front happens when a cold front or a warm front stays in place for (14)  several   days without invading another front. Clouds, light winds, and precipitation often form at the (15)  boundary  . The precipitation may last for several days.
     An occluded front develops when two masses of cold air (16)  meet  . The cold air forces warmer air caught between the two fronts upwards. Cumulonimbus and stratocumulus clouds usually form. Strong winds and heavy rain or snow may result.
     Why do you think precipitation usually happens along a front? In most fronts, warm air (17)  meets   cooler air. As warmer air cools, it can hold less water. That's why some form of precipitation usually occurs.

Answers to Reading Comprehension Questions

1 Large pockets of air that may cover ten thousand or more square miles
2

Where they form
3

Cyclones
4

Rain and/or thunderstorms
5

  Stationary front
6  The weather changes and precipitation usually occurs.
7

All of the above
8

All of the above
9

True
10

Ratio of oxygen/nitrogen