By : Erin Taylor

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.

Winds in this area are gentler.

Isobars also indicate the locations of high-and low-pressure areas.

Temperature is defined as the level of thermal energy, where temperature is the driving force of thermodynamic flow. 

Three of the most commonly used scales for measuring temperature are : Celsius or Centigrade = C Fahrenheit = F Kelvin = K 

Air pressure changes with altitude. When you move to a higher place, say a tall mountain, air pressure decreases because there are fewer air molecules as you move higher in the sky.

If a high pressure system is on its way, often you can expect cooler temperatures and clear skies. If a low pressure system is coming, then look for warmer weather, storms and rain.

Air pressure is the weight of the atmosphere pressing down on the earth. It is measured by a barometer in units called millibars. Most barometers use mercury in a glass column, like a thermometer, to measure the change in air pressure.