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Weather Maps

Weather Maps

If you want to know the current weather conditions, you can look out a window or step outside. You can tell if it is precipitating, if it is hot or cold, and how much of the sky is covered by clouds. But, what if you want to know what the weather will be like tomorrow? Then, you are better off looking at a weather map.

A weather map illustrates the weather conditions for an area at a given time. Weather stations provide surface data about temperature, humidity, precipitation, wind, and air pressure. Weather balloons are used to collect similar information but from higher in the atmosphere. Weather satellites monitor surface and atmospheric conditions and help track severe weather. Radar locates and tracks precipitation. Meteorologists, scientists who study the weather, use data from all of these sources to create weather maps. They analyze patterns on weather maps to predict future weather. Today, sophisticated data collection, weather maps, and computer models help meteorologists forecast and predict weather with more accuracy then in the past.

There are different types of weather maps. A common weather map is the surface analysis map which shows the weather conditions for an area for a specific time. A surface analysis map may include symbols indicating information about weather fronts, air pressure and temperature, wind speed and direction, cloud cover, and precipitation type and intensity. The table below shows the map symbols for the different weather fronts.
Weather Front Symbols
Symbol - Cold FrontCold Front
Symbol - Warm FrontWarm Front
Symbol - Stationary FrontStationary Front
Symbol - Occluded FrontOccluded Front

Along with fronts, weather maps typically show high and low pressure systems. A high pressure system is shown by an uppercase H. High pressure systems are anticyclones that produce clear, dry weather. A low pressure system is shown by an uppercase L. Low pressure systems are cyclones that are often associated with wind, clouds, and precipitation.

Many weather maps have curved lines drawn on them. An isobar is a line that show equal atmospheric pressure. Isobars circle around areas of high and low pressure. They are labeled in units of millibars (mb). Closely spaced isobars usually mean windy conditions. Another type of line you may see on a weather map is an isotherm. An isotherm is a line that shows equal temperature. Isotherms may be labeled in degrees Fahrenheit or Celsius.

The weather maps shown on television or in a newspaper may look different than maps made by the National Weather Service. For example, media weather maps may show colorfully illustrated symbols instead of simplified black-and-white symbols. The table shows a sampling of the types of precipitation symbols you may see on a weather map.

Examples of Weather Map Precipitation Symbols
[math],[/math]Intermittent Drizzle
[math], ,[/math]Continuous Drizzle
[math]*[/math]Intermittent Light Rain
[math]* *[/math]Continuous Light Rain
[math]vdots[/math]Intermittent Heavy Rain
[math]**[/math]Intermittent Light Snow
[math]** **[/math]Continuous Light Snow
[math]harr[/math]Ice Needles


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