Atmospheric Pressure

What is pressure? The amount of force per unit of area

What is atmospheric pressure? The force caused by the weight of air 15 pounds per square inch (lbs/in2) Or 1 kilogram per square centimeter (kg/cm2)

How is air pressure exerted on us at the surface of the earth? Like this In ALL directions Not like this

Which weighs more? Dry Air Moist Air O O H H O N N Oxygen (O2) Atomic Mass = 32 Water Atomic Mass = 18 N N Nitrogen (N2) Atomic Mass = 28

What affects the amount of air pressure exerted on the surface of the earth? Temperature: temperature air pressure Elevation: elevation air pressure Moisture content: moisture air pressure Density: density air pressure

Measuring Atmospheric Pressure Barometer

Isobar                                                                                                                                                                              Lines on a weather map that connect locations with the same air pressure

Atmospheric Heating

Convection The motion or movement of large groups of molecules based on their relative densities or temperatures. (Warm air rises-less dense- and cool air moves in to replace it.)

Conduction Conduction is the direct transfer of energy through direct contact between atoms.

Radiation The method by which the sun's energy reaches the earth. All objects radiate: hotter ones radiate more. Two objects at the same temperature, and the same size do not radiate the same amount of heat.

Describe heat transfer in the Earth Radiant energy from the sun heats the surface of Earth Through conduction Earth heats the air in contact with it; Through convection the warm air rises and is replaced by cool air, the warm air cools and sinks back to the surface

How does a thermometer work? The liquid inside expands when heated, rising up the tube it contracts when cooled and gets lower