Severe Weather How to Read a Weather Map Unit 11 – Day 2

Warm and Cold Fronts Blue lines are cold fronts and red lines are warm fronts. High and Low Pressure Systems –A _________ means a center of high pressure (usually calm, sunny weather). –A red "L" means low pressure (which can mean storminess). Most fronts extend from low-pressure centers.

How would you read the cold and warm fronts on this map? In which directions are they going?

Weather Station Symbols Cloud Cover Each circle represents a weather station. The circle at each station is empty if skies are clear. The circle is white if it’s cloudy. A line within the circle or a half-filled circle means "partly cloudy." Wind and Wind Direction The little arrows attached to each weather station point in the direction the wind is blowing from. The more barbs at the end of each arrow, and the longer they are, the harder the wind is blowing. Each long barb is 10 knots. Each short barb is half that amount.

Weather Station Symbols Air Temperature The number to the upper left of each station is the air temperature in degrees F (for U.S. maps) or degrees C (for other countries). Dew Point The number to the lower left of each station is the dew point temperature in degrees F (for U.S. maps) or degrees C (for other countries). The dew point is a measure of moisture; it shows how much you'd have to cool the air to get a relative humidity of 100 percent. The higher the dew point, the more water vapor there is for producing rain or snow.

Weather Station Symbols Barometric Pressure The number to the upper right of each station is the barometric pressure. Standard air pressure is 1013mb. (14.7lb/sq. in.)