GRADE: Seventh

CONTENT STANDARD: Earth and Space Science

CONTENT TOPIC: Structure of the Earth

CONCEPT: The earth's weather is an interaction of all parts of the environment.

CONTENT OBJECTIVES: 7I6.00 To understand how meteorologists predict weather

INSTRUCTIONAL OBJECTIVES: The learner will:

6.01 define meteorologist.
6.02 investigate characteristics of the atmosphere important to the meteorologist
6.03 make weather predictions for the local area based on weather maps

I. Definition of meteorologist
II. Characteristics of the atmosphere
A. Air masses
1. Region of origin
a. Polar
b. Tropical
2. Material of origin
a. Water (maritime)
b. Land (continental)
B. Types of Fronts
1. Cold front
2. Warm front
3. Stationary front
4. Occluded front
C. Temperature
D. Wind
1. Speed
2. Direction
E. Air Pressure

TN COMPONENT OF SCIENCE: Habits of Mind

TN GOAL:

To enable students to demonstrate ways of thinking and acting inherent on the practice of science; and to exhibit an awareness of the historical and cultural contributions to the enterprise of science.

3.3 ESTIMATION AND COMPUTATION - Scientists judge the level of precision needed to approximate a reasonable response without the aid of mechanical devices.

3.3a Estimation provides a way to judge, if the result of a comparison is reasonable.

BENCHMARK: Estimation of probability can be based on data from similar conditions in the past or what is known about current situations.

TIME REQUIRED:

Two to three class periods

Weather maps from newspapers

Cold front, continental air mass, maritime air mass, meteorologist, occluded front, polar air mass, stationary front, tropical air mass, warm front

Have you ever wondered who says it will rain today or that it will be sunny and hot? (response) Have you ever wondered how the weather forecasts are made? (response) Today we will learn about the meteorologist who forecasts the weather and we will investigate some of the characteristics of the atmosphere which have to be considered before a forecast can be made .

Meteorologists are scientists who study the atmosphere and the changes that take place in it. Meteorologists from all over the world work together to provide us information about the kind of weather for a twenty-four hour period. They record information about such weather characteristics as temperature, air pressure, winds, clouds, humidity, precipitation, and visibility.

The best known meteorologist to us is probably the weather person we have seen on television. Although all weather people are not trained meteorologists, many are. If the local weather person is not a meteorologist, the information they provide has been received from a meteorologist. We pay close attention to the local weather person because we usually want to know what the weather forecast is, so we know how to dress for school, whether we will be able to have a picnic or play baseball. There are others who have a much greater reason for wanting to know about the weather. A farmer needs to know what the weather forecast is in order to decide to cut hay for baling, since the hay must dry for several days before it is baled. A pilot needs to know about the weather in order to insure passengers a smooth and safe flight. Can you think of other people who may have a serious interest in the weather forecast? (response)

The meteorologist is able to forecast the weather because of the data provided by a large number of meteorologists. If the weather is accurately recorded for the whole world four times daily on weather maps, changes in the weather can be seen from one time period to the next for a particular region of the world. Studying these changes which have actually happened allow the meteorologist to predict or forecast what is likely to take place over a period of time for a given area with a very high degree of accuracy

Confidence in this ability frequently leads to forecasts which are five days from the time of the forecast The need for weather information is so great that a special cable television channel, The Weather Channel, has been founded. One of the regular segments on The Weather Channel is the "five day forecast." Needless to say, the shorter the time involved in the forecast, the more accurate the forecast.

In order for a meteorologist to make a forecast, even with a weather map, a great deal of training is required .This training includes a lot of study in science which is very similar to material you have studied.

Most weather systems which affect the United States move from west to east In order for the meteorologist to understand weather systems they must know about air masses Air masses are generally classified as tropical or polar, with the tropical air masses originating over the tropical regions and the polar originating over the polar regions These air masses may originate over water (maritime) or land (continental) While tropical air masses are hot, polar air masses are cold if the air mass originates over water it will be humid, but if it originates over land it will be dry. Thus a polar air mass originating over land will be cold and dry As polar sir masses move south they warm up, while tropical air masses cool as they move north. As the hot and cold air masses move across the United States they often come together. The place where a hot air mass and a cold air mass meet is called a front.

A cold front results when a cold air mass meets a warm air mass. The warm air is pushed up and away, while being cooled. Clouds are formed The result may be rain or even a thunderstorm. When the front moves on clear skies return and the temperature drops. A war-front takes place when warm air meets cold air and the warmer air slides over the cold air. Condensation occurs and a drizzle or slow steady rain may result When neither of the air masses can overpower the other a stationary front takes place and may not move for a long time. A long steady rain is usually associated with this type of front. You have probably seen one of these fronts in the sky. Have you ever seen clouds in the sky which appeared as a long line? (response)

All three of these fronts are in contact with the ground. An other kind of front which is not in contact with the ground is an occluded front. The occluded front may begin as a stationary front with cold air moving on the west side of the line made by the front, while the warm air moves on the east side of the line. Eventually the cold air lifts the warm air above it, so that the warm air is over cold air while still being pushed by the cold air mass. Occluded fronts always bring precipitation.

Temperature, wind speed and wind direction are important in the forecasting of weather, but air pressure is another characteristic of the atmosphere which interests the meteorologist. Air pressure drops and rises as it passes through, thus giving yet another clue as to what is to come.

Certainly one of the challenges confronting a meteorologist would be trying to determine when two unlike air masses are likely to meet, where they would come in contact, and what type of front would be formed. In addition to the above information, the meteorologist would need to consider the characteristics of the geographical areas and the season in order to make a prediction about the weather which might result.

(Try the following activities):

1. Have the students cut the weather maps from USA TODAY or the local newspaper and track weather systems which are approaching your area. After several days of study, have students make predictions as to what the weather will be in 24 hours, 48 hours, etc. They can make comparisons between their predictions and those reported in the newspaper or on television.

2. Have students research to identify instruments used by meteorologists.

3. Have students construct instruments which can be used to record weather data.

Can you tell me what a meteorologist does? (response) What are some of the instruments which are needed in order to forecast the weather? (response) Tell your partner why it is so hard to be accurate when you are forecasting the weather? (pause, then review answers)

cold front - line formed when a cold air mass meets and pushes back or replaces a warm air mass

continental air mass - air mass which originates over land

meteorologist - study of the earth's atmosphere

occluded front - line between the coldest air of a cold front and warm air with cool air under it

polar air mass - air mass which originates in the polar region

stationary front - line formed when a warm air mass meets a cold air mass and neither overpowers the other

tropical air mass - air mass which originates in the tropic region

warm front - line formed when a warm air mass moves over a cold air mass

This is the time this file has been accessed since 04/02/98.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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