|Earth and Space Science||Meteorology 4K2.00||Habits of Mind||Assumptions 3.2 acd|
Sponsored by the National Science Foundation
CONTENT STANDARD: Earth and Space Science
CONTENT TOPIC: Meteorology
CONCEPT: Atmospheric conditions vary.
CONTENT OBJECTIVE: 4K2.00 To understand weather and the effect of changing atmospheric conditions
> INSTRUCTIONAL OBJECTIVES: The learner will:
TN COMPONENT OF SCIENCE: Habits of Mind
BENCHMARK: Unknown or unobserved variables may lead to unanticipated results.
3.2c The critical assumptions behind any line of reasoning must be made explicit so that the validity of the position taken can be judged.
BENCHMARK: Prior learning must be accurate and free of incorrect assumptions.
3.2d The validity of an investigation cannot be accepted unless the complete investigation can be independently duplicated.
BENCHMARK: Scientific truths must be supported by data in conjunction with logical evaluations.
An air mass has nearly horizontally uniform temperature and moisture conditions. This means that for a long distance, at the same altitude, the temperature will be the same. It may be hot air (Tropical mass) cold air (Polar mass) moist air (Maritime) or dry air (Continental). Weather forecasting is based on information about air masses, high-low pressure systems and the movements of fronts. Air masses travel east across the United States. Different air masses meet along the way, but they usually don't mix. The surface between the different masses is called a FRONT. The forward edge of a cold air mass is called a COLD FRONT. The forward edge of a warm air mass would be a WARM FRONT. Sometimes cold and warm air masses stay in one place for a while. They do not move. When they don't move, they are called STATIONARY FRONTS. This means the weather will not change for awhile. An OCCLUDED FRONT is caused when masses of cold air have raised a warm air mass from the ground.
Sometimes weather forecasters will say something about high pressure or low pressure. These pressure areas are important to weather forecasters because certain kinds of weather can be expected with each kind of pressure area. Because cool air is heavier than warm air, the barometric pressure would go up when a cold air mass moved in. The weather in a high pressure area is usually fair. Most of the time high pressure means no clouds and fair weather. Because warm air is lighter then cool air the air moving up would make a low pressure area. This also makes clouds. Most of the time, a low pressure area means bad weather.
All of the above affects the temperature. During all of this, there would continue the cycle of water vapor (Water in the air as gas) evaporation (Water that can be seen, becoming water that cannot be seen) and condensation (Water that cannot be seen, becoming water that can be seen).
This is the time this file has been accessed since 07/01/97.
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