Pressure Changes with Altitude State the relationship between height (altitude) and pressure Pressure reduces in half for each ______ km 5

1% of the atmosphere 10% of atmosphere

Air Pressure Is Proportional to Density (density is how “packed” the molecules are per unit area) At HIGH altitudes, the air is “thin”, Pressure is less At LOW altitudes, near the surface, there are more air molecules, so pressure is greater.

Factors that Affect Air Pressure Density (altitude or elevation) Temperature Humidity (water vapor)) Weatherbug graph activity

Pressure Changes with Temperature Warm air molecules have a lot of energy, are widely spaced apart – less dense, and exert less, LOW pressure. Cold air contains slow moving molecules that are packed closely together (very dense) and exert HIGH pressure.

Air Pressure and Aviation Altimeter: measures altitude by detecting change in air pressure

Temperatures vary due to UNequal heating of earth’s surface Earth’s seasonal orbit around the Sun Thickness of Earth’s atmosphere Angle of the sun 23.5 degree tilt on axis

Temperature changes with Humidity (water vapor in the air) Increase in water vapor (humidity) causes… Air: N2 _____ and O2 _______ 14 x 2 16 x 2 = 60 Water vapor: H2O 2 Hydrogen ____ Oxygen ______ 1 x 2 16 = 18 air to be LESS dense = less, LOW pressure

Relative Humidity and air Pressure

Upper atmosphere winds (Jet Stream)

Upper Air-flow patterns cause Surface High and Low pressure https://www.youtube.com/watch?v=aiYyCurh_SU WGN explains

Convergence and Divergence Air converges, piles-up and is forced upward. More air in a taller column Causes vertical clouds and precipitation Cold air sinks, and is forced to spread-out at the surface. No clouds form – clear, fair weather

http://darktimeschronicle. wordpress http://darktimeschronicle.wordpress.com/what-are-high-and-low-pressure-systems/

Cyclone Anticyclone

What direction is this cyclone rotating?

in the Northern and Southern Hemispheres Cyclonic Circulation in the Northern and Southern Hemispheres