Composition of the Atmosphere

Air Density Temperature –Warmer air is less dense than cold air Humidity –Humid air is less dense, dry air is more dense Air is Never Completely Dry –Water vapor is as much as 4% of its volume

Adiabatic Cooling and Heating Air becomes cooler when it expands –As air rises, it expands and cools Air heats up when it is compressed. –As air sinks, it compresses and heats up Warm air holds more water vapor than cold air –When warm air cools, water vapor condenses and forms precipitation

Earth’s Heat Budget

Uneven Solar Heating &Latitude

Convection Currents

Coriolis Effect Any object moving freely across the globe appears to curve slightly from it initial path. In the N. Hemisphere it curves to the right, in the S. Hemisphere it is to the left. Observed deflection caused by observer’s moving frame of reference »Every point on the earth’s surface moves eastward at 15°/hour, but points closer to the equator move faster than those closer toward the poles

Latitude and Speed Every point on the earth’s surface moves eastward at 15°/hour But points closer to the equator move faster than those closer toward the poles

Inter-Tropical Convergence Zone

ITCZ and Monsoons Monsoons linked to –the different specific heats of land and water –the annual north-south movement of the ITCZ, InterTropical Convergence Zone. EX: In Asia, the landmass draws warm, moist air from the Indian Ocean. Southerly winds drive moisture toward Asia where it rises and condenses to produce a months-long deluge

Sea Breezes and Land Breezes Sea breeze: Cooler air over the sea moves toward land as the land heats up Land breeze: At night, cooler air on land is pushed offshore as warm air from the ocean rises.

Tropical Cyclones Great masses of warm, humid, rotating air. –Large tropical cyclones are called hurricanes in the N. Atlantic and E. Pacificand typhoons in the western pacific Wind speeds must be in excess of 119 km/hr (74 mph) Generated within one warm, humid air mass –Strength comes from the heat energy that is released when water vapor condenses as liquid. Tons of energy –Rain fall can be 1 inch/hour or 20 billion metric tons/day –One day releases 2.4 trillion kWh, the energy needs for the U.S. for 1 year