How can you Interpret a Weather Maps?

Weather Maps are used to show the current state of the atmosphere and to forecast future conditions.

Isolines connect points of equal MEASURMENTS. Isotherms connect points of equal TEMPERATURE Isobars connect points of equal PRESSURE

Isotherms Isobars

Pressure Gradient - Is the rate of change in air pressure. -The closer the isobars the greater the pressure gradient - The greater the pressure gradient the greater the wind speed.

Isobars close together = high pressure gradient = fast wind speeds Isobars far apart = small pressure gradient = slow wind speeds

Rules for Drawing Isolines 1.Isolines don’t cross each other! (Although sometimes they come very close together) 2. Isotherms should run east – west. (The higher the latitude, usually the colder the isotherm) 3. Isobars should make circles of high and low pressure

Isoline Example: Isolines connect points of equal value, draw the line through the center of the number (or point)  15 55 55  10

Isolines are gentle, curving lines; no sharp corners. (THESE ARE BAD CONTOUR LINES)  15 55 55  10

Isolines NEVER cross - **this would mean that one point has two different values.** 20° 30 ° 40 ° 50 °60 ° XX YY ZZ The red line is WRONG  The black lines are RIGHT

Isolines usually are parallel. (They have a parallel trend.)

Worksheet – “Isobars – Wind and Air Pressure”