CSET 118: Energy in the Earth System

• evaporation - liquid water molecules absorb energy and are changed to water vapor
• transpiration - plants take water from the soil, pass it through, and give it off from the surface of the leaves
• condensation - water vapor cools and returns to liquid state
• precipitation - water falls to the surface of the Earth when the clouds become heavy with moisture 

• precipitation on impermeable surface - runoff  eventually flows downhill to larger body of water and make its way back to the ocean 
• precipitation infiltration into soil, groundwater - water that fills the cracks and pores in the rock layers and soil underground, slowly flows downhill to large bodies of water

• axial tilt - Earth's axis of rotation is tilted with respect to its plane of orbit around the Sun 
• day length is different throughout the year, different is greater near than the poles than the equator
• Sun's intensity is highest around noon when it is at its highest point each day 

• summer solstice - Northern Hemisphere is tilted most toward the Sun, longest day of the year, shortest in Southern Hemisphere
• winter solstice - Northern Hemisphere is tilted farthest away from the Sun, shortest day, Southern has longest day 

seasons - at any time of the year, one portion of the planet receives more solar radiation than the other, more pronounced at summer/winter solstices

• the amount of solar radiation that strikes the Earth varies with latitude - causes seasons 
• the height of the Sun determines the amount of sunlight that reaches the ground
• where the sun is directly overhead - rays strike perpendicular and energy is concentrated to small area
• area not directly beneath the Sun - same amount of energy spread over broader area

• atmospheric circulation - from the difference in the amount of solar energy received at the equator versus the poles 
• convection cells - 6 around the globe 

• pressure zones - air rises at a low pressure zone and sinks at a high pressure zone 
• pattern of rainfall matches the vertical limbs of the convection cells 

• heat distribution - heat moves vertically in a convection cell as warm air rises and cold air sinks 
• heat moves horizontally at the equator and moves toward the poles
• helps to distribute heat more evenly

• wind - horizontal movement of air  
• Coriolis effect - deflection of winds because Earth is rotating beneath 

• global wind belts - formed from the bottom limbs of the major convection cells 
• blow north or south with a curve due to Coriolis effect 

• jet streams - winds that have enormous influence on weather and climate 
• rivers of air suspended in the atmosphere 
• found where there are large differences in temperature between two masses of air - where major global convection cells meet 

proximity to ocean influences climate - oceans moderate temperature because large bodies of water can absorb or release heat 

mountains are barriers to weather patterns and influence climate 

• land and sea breezes - wind is created by air moving from high pressure to low pressure zones 
• the temperature differences between the ocean and nearby land creates breezes

• radiation - Earth's surface is heated by radiation from the Sun 
• conduction - how we feel heat on our feet from the pavement 
• convection - air or magma rise and sink, constant transfer creates a convection current
• in the asthenosphere - primary way heat is transferred within Earth  
• in the atmosphere - from differences in temperature between the poles and the equator, Sun is the source of energy

 cold weather fronts - form when a fast-moving cold air mass over takes a warm air mass, the warm air is pushed upward along edge of the front and cools, releasing its water vapor -> clouds, rain, snow 

 warm front - when a warm air mass overtakes a slower cold air mass, warm air mass will rise up over the cold air mass -> creates cloudy conditions, warm humid weather 

 stationary front - cold air masses and warm air masses meet, days of steady rain, snow, cloud or fog 

 occluded fronts - a warm air mass gets caught between two cold air masses, cooler air moves under warm air mass pushing it up, warm air eventually cools -> cloudy weather with a chance of snow or rain 

• L - low atmospheric pressure -> wet, windy
• H - high atmospheric pressure -> dry, clear weather 

 wind speed and direction shown with arrows 



isobars - lines that connect places with the same pressure

isotherms - connect places of equal temperature