GLOBAL ENERGY BUDGET - 3 Atmosphere Basics
ATMOSPHERIC COMPOSITON
ABUNDANT NON-GREENHOUSE GASES Nitrogen Inert As N important role in biological cycles Oxygen Reactive Respiration Argon Byproduct of potassium decay
Anthropogenic
ATMOSPHERIC PRESSURE Influences climate & radiation budget Force per unit area Pressure at Sea Level 1 atmosphere (1 atm) 14.7 lbs/in2 1.013 bar 1013 millibars
ATMOSPHERIC PRESSURE Barometric Law – the pressure decreases exponentially with altitude a factor of 10 for every 16 km increase in altitude Pressure decreases faster with increasing altitude when the air is colder
ATMOSPHERIC PRESSURE
ATMOSPHERIC TEMPERATURE THERMOSPHERE MESOSPHERE STRATOSPHERE TROPOSPHERE
METHODS OF HEAT TRANSFER Convection – transfer of heat energy by moving fluids generated when fluid heated from below Conduction – transfer of heat energy by direct contact between molecules Radiation – transfer of heat energy by electromagnetic waves emitted from a body
TROPOSPHERE Lowest layer Temperature decreases rapidly with altitude 0 - ±15 km Important in climatic studies Where weather occurs Well mixed by convection
TROPOSPHERE Incoming solar energy absorbed by surface (land and water) Energy re-radiated as IR radiation IR radiation absorbed by greenhouse gases & clouds Energy transported by convection (well-mixed) Where atmosphere more transparent to IR, energy then radiated from Earth
LATENT HEAT Heat energy absorbed or released by the transition form one phase to another – solid, liquid, gas
STRATOSPHERE ±15 – 50 km Temperature increases with altitude Pressure much lower Contains most of Earth’s ozone Very dry - <5 ppm water vapor Non-convective, less well mixed
MESOSPHERE 50 – 90 km Temperature decreases fewer air molecules to absorb incoming EMR small amounts of ozone prevent the air from warming
THERMOSPHERE 90+ km Temperature increases rapidly Aurora Borealis due to the absorption of huge amounts of incoming high energy solar radiation by atoms of nitrogen and oxygen Aurora Borealis
EXOSPHERE Outermost fringe of the atmosphere Infrequent molecular collisions
ATMOSPHERIC TEMPERATURE THERMOSPHERE MESOSPHERE STRATOSPHERE TROPOSPHERE
VERTICAL TEMPERATURE PROFILE Troposphere - Ground absorbs sunlight, heats atmosphere above Stratosphere - Ozone absorbs solar radiation Maximum heating occurs at top of layer Mesosphere - Ozone & heating rate decline Thermosphere - O & N absorb shortwave UV radiation