LESSON 5 - ACTIVITY 5 - PLOTTING FRONTS
Materials
Background Information
Key Questions
Vocabulary
Procedure
Evaluation
Objectives
- Identify areas of cold and warm air
- Plot and chart cold and warm fronts
- Identify the direction weather moves across the US
Materials
- 4 overhead transparencies of weather maps from local newspaper
- blank transparency or US outline map
- 10 days of consecutive weather maps from your local newspaper per student or group
- 10 index cards per student or group
- glue
- scissors
Background Information
We learned in the last activity that low pressure systems generally produce stormy weather, and high pressure systems generally produce fair weather. We also learned that the two pressure systems create wind patterns that rotate in opposite directions. In the Northern Hemisphere, low pressure systems always creates winds that rotate counterclockwise. High pressure systems always create winds that rotate clockwise. The winds generated by high and low pressure systems play a major role in moving warm air from the south and cold air from the north. This movement of air masses creates weather fronts. A weather front is an area located between two air masses that have different characteristics such as humidity or air temperature. There are four different classifications of weather fronts.
Cold front: occur where a cooler air mass meets a warm air mass. The colder air, situated lower because it is more dense, cuts under the warmer air, lifts it and finally overtakes it. Cold fronts travel rather fast. Powerful cold fronts can create thunderstorms, tornadoes, squall lines, high winds and snowstorms and cooler, dry weather once it has passed. On a weather map, cold fronts are shown as a blue line with triangles that point in the direction that the front is moving.
Warm front: occur where a warmer air mass meets a cold air mass. The warm air rises up & over the cooler air. Warm fronts travel slower than cold fronts, and produce less severe weather. They settle over a cold front and push it away. Warm fronts produce steady, lighter snow or rain ahead of them, which last a few hours to many days, and warm, dry air once it has passed on. On a weather map, warm fronts are shown as a red line with half circles that point in the direction that the front is moving.
Stationary front: is an area between two different air masses, where neither of the fronts is strong enough to displace the other one. Many different weather patterns can be associated with a stationary front but you'll usually find clouds and long periods of precipitation. Stationary fronts generally move out in a few days, or will turn into a warm or cold front. Stationary fronts are found more in the summer. On a weather map, a stationary front is shown as an alternating red and blue line with half circles & triangles that point in opposite directions. The long periods of precipitation found with stationary fronts are often responsible for floods in the summer.
Occluded fronts: form when a slow moving warm front is in front of a fast moving cold front. The cold front overtakes the warm front & pushes it higher. The two fronts move along together, and the line that forms between them is the occluded front. Many different weather patterns can be associated with an occluded front, but you'll usually find stratus clouds & light precipitation. On a weather map, occluded fronts are shown as a purple line with triangles and half circles that point in the same direction. They usually form near low pressure areas when the area of low pressure is weakening. It is sometimes called a Trowal which stands for Trough of Warm air Aloft.
Key Questions
- How are warm and cold fronts identified on a weather map?
- How would you plot a front on your weather map?
- In what direction does weather generally move across the US?
Vocabulary
- fronts
- cold front
- occluded front
- stationary front
- warm front
Have your students create a flip-book to illustrate how weather fronts move across the US.
Materials
- 10 days of consecutive weather maps from your local newspaper per student or group
- 10 large index cards per student or group
- glue
- scissors
Procedure
Number the weather maps so the order can be recreated after they are cut out. Cut out the weather maps. Glue the weather maps onto the index cards. Place the weather maps in numerical order with the lowest number on top and staple them together along the left edge. Flip the book from front to back to see the weather in motion. Ask your students in which direction the weather fronts moved. Weather in the US generally moves in a West to East manner.
Alternative materials:
Posterboard or any stiff paper may be used instead of index cards. It may also be more cost effective to use a copier to generate one or two pages with all ten weather maps as long as the information included on the weather maps is not too small to read.
Procedure
- On the chalkboard, draw an L and an H. Review with your students in which direction winds rotate around high or low pressure systems.
- Create an overhead transparency of a weather map and have your students locate the areas of high and low pressure. Ask for volunteers to state the wind direction for each.
- Create overhead transparencies of weather maps for 4 consecutive days. Use the first three of these to demonstrate the paths of the pressure systems from one day to the next by placing them on top of each other one at a time in date order. Use an overhead transparency of a blank outline map of the US. Generate discussion among your students as to where they think the front will move next. You can verify their predictions by overlaying a fourth overhead transparency of the weather map.
- Use a current weather map from your local newspaper and ask for student volunteers to locate and circle the following items on the map: low pressure areas, high pressure areas, warm fronts, cold fronts, rain, thunderstorms, or snow.
- Allow your students sufficient time to access the internet to collect data for weather fronts for the 13 weather stations. They should become more familiar with the internet site the more times they access it, resulting in less time spent collecting data. They will indicate the cold and warm fronts on their weather maps and add the information into a spreadsheet.
- Students will locate the two warmest stations on their weather map and mark the area between the as warm. Students will locate the two coldest stations on their weather map and mark the area between the as cold.
Evaluation
- Students will be able to locate and plot cold and warm air masses.
- Students will be able to predict the path of cold and warm air masses.
- Students will be able to identify the direction weather moves across the US.
