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| Weather Observations You can determine current weather conditions by making observations such as checking a thermometer for temperature and looking to see whether clouds are in the sky. You have a general idea of the whether in your area because you are familiar with the typical weather. What weather concerns do you have in your region?  A meteorologist is a person who studies the weather. Meteorologists take measurements of temperature, air pressure, winds, humidity, and precipitation. Computers, weather satellites, Doppler radar, and instruments attached to balloons are used to gather data. Meteorologists use the information provided by weather instruments to make weather maps and these maps are used to make weather forecasts.  Forecasting Weather: Meteorologists gather information about current weather and use computers to make predictions about future weather patterns. Because storms can be dangerous, you do not want to be unprepared for threatening weather. Meteorologists cannot always predict the weather exactly because conditions can change rapidly. The National Weather Service depends on two sources for its information-data collected from the upper atmosphere and data collected on Earth's surface. Meteorlogists of the National Weather Service collect information recorded by satellites, instruments attached to weather balloons, and from radar. This informatin is used to describe weather conditions in the atmosphere above Earth's surface. Station Models: When meteorologists gather data from Earth's surface, it is recorded on a map using a combination of symbols, forming a station model. A station model shows the weather conditions at a specific location on the Earth's surface.  Temperature
and Pressure:
 In addition to station models, weather maps have lines that connect locations of equal temperature or pressure. A line that connects locations of equal temperature is called an isotherm. Iso means "same" and therm means "temperature."  An isobar is a line drawn to connect
points of equal atmospheric pressure. You can tell how fast wind
is blowing in an area by noting how closely isobars are spaced.
Isobars that are close together indicate a large pressure difference
over a small area. A large pressure difference causes strong
winds. Isobars that are spread apart indicate a smaller
difference in pressure and mean winds in this area are gentler.
Isobars also indicate the locations of high- and low- pressure areas. |
Weather
Maps: On a weather
map, pressure areas are drawn as circles with the word High or Low in
the middle of the circle. Fronts are drawn as lines and
symbols. When you watch weather forecasts on television, notice
how weather fronts tend to move
from west to east across the United States. This is a
pattern that meteorologists depend on to forecast weather. |
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