M ETEOROLOGY : T HE S CIENCE OF W EATHER Key variables for determining Earth’s weather Rotation of the Earth Revolution of the Earth Radiation received from the Sun Composition of the Atmosphere Nitrogen – 78% Oxygen – 21% Argon – 1% Water vapor & other gasses (solids – dust particles) Grows thinner with altitude Figure 22.2 & 22.3 Mt. Everest – one-third compared to sea level

M ETEOROLOGY : T HE S CIENCE OF W EATHER Mt. Everest 29,029 ft.

M ETEOROLOGY : T HE S CIENCE OF W EATHER Atmospheric Pressure Pressure from the weight of the atmosphere above you At sea level 14.7 lbs./sq. in. Decreases with altitude What does this feel like? Popping ears Barometer Water Mercury (1643) in. (sea level )

M ETEOROLOGY : T HE S CIENCE OF W EATHER Atmospheric Warming Heating the Earth Convection Radiation Energy Budget (Figure 22.6) 51% absorbed by Earth’s surface 20% reflected by cloud & other atmospheric material 16% absorbed by the air Greenhouse Effect Lapse rate 3.5 degrees / 1,000 ft. Wind Chill & Heat Index

M ETEOROLOGY : T HE S CIENCE OF W EATHER Structure of the Atmosphere Distinct layers – determined by change in temperature (Figure 22.8) Troposphere (0-6 mi.) Temperature decrease stops The weather sphere Stratosphere (6-30 mi.) Temperature begins to rise Mesosphere (30-50 mi.) Temperature begins to decrease again Thermosphere Temperature increases again

M ETEOROLOGY : T HE S CIENCE OF W EATHER Wind Determined by the direction of origin Variables causing wind Temperature & density (vertical) Warm air rises Decreases pressure Cold air sinks Increases pressure Air pressure (horizontal) High pressure to low pressure Figure 22.9 Effects of water Figure Sea Breeze - Day Land Breeze - Night

M ETEOROLOGY : T HE S CIENCE OF W EATHER Global Wind Patterns Effected by temperature & pressure Prevailing westerlies Northeast trade winds Horse latitudes Water & the Atmosphere Humidity Relative humidity Psychrometer Dew point Frost