Chapter 8

1. Chapter 8 Air-Sea Interaction

2. The Solar Connection • Life gets almost all energy from the sun • Solar energy provides energy, drives winds, and drives currents in the ocean • Temperature relies on sunlight • The sun provides life and the conditions in which life exists.

3. Air and Sun • Air is a mixture of gases that surround us • 4 layers of the atmosphere: • Troposphere- lowest layer; more concerns with us • Stratosphere: next layer above troposphere • Mesosphere: next layer above stratosphere • Thermosphere- top layer which goes out into space

4. Air and Sun • Amount of water vapor (water as a gas)in the air relates to air temperature, density, and pressure. • Temp. rises, air pressure increases, and density decreases -Adding water vapor decreases the density even more -Warm air is less dense than cool air • When a saturated or nearly saturated air mass cools it has more water vapor in it than it can hold. The vapor condenses, forming rain when the temperature is above freezing or snow when the temp is below freezing.

5. The Earth’s Heat Balance • 50% of all sunlight that reaches the atmosphere makes it to Earths surface • To maintain balance with the heat from the sun, all the energy absorbed reradiates through various paths back into space as infrared radiation • If more heat came than left, Earth would grow hotter and hotter until life perished.

6. Uneven Heating • Factors that cause Earth to heat unevely: • The earth is round • Earths axis is tilted • Earths orbit is elliptical so the distance between Earth and sun varies with time of year • Uneven heating causes weather- in part due to convection: vertical- circular currents caused by temperature differences in a fluid such as air. Creates a circular airflow pattern.

7. Deflection to the Right or Left • Coriolis effect: tendency for the path of a moving object to deflect to the right in the Northern Hemisphere and to deflect to the left in the Southern Hemisphere. • Caused by the Earths rotation relative to an object in motion over its surface; • Creates circular airflow and current patterns such as the major ocean gyres: in the Northern Hemisphere to the right and in the Southern Hemisphere to the left

8. The Coriolis Effect and the Wind • The Coriolis Effect deflects the air to the right in the Northern Hemisphere giving the air a circular airflow pattern rather than straight north-south pattern. • Atmospheric circulation cells are six distinct air masses with certain airflow patterns • Most important of these six air masses are the Hadley Cells: lie between the equator and approximately 30˚ north or south latitude • Trade winds: caused by air rising at the equator and moving northward. • Ferrel Cells: wind that descends from the Hadley cells that continues on toward the poles shifting to the right as it moves; causes the Westerlies(from the west)

9. ITCZ: Intertropical Convergence Zones • ITCZ equator marks the temp equilibrium between the hemispheres that shifts north and south of the geographic equator • Important because ocean circulation and atmospheric circulation are symmetrical on either side of the ITCZ equator • Downward vertical airflow brings dry air to Earths surface-leading to areas with little rainfall and significant evaporation • This makes salinity of these waters higher than average

10. Monsoons and Cyclones • Monsoons: seasonal wind pattern changes caused by heating or cooling on the continents; cause summers with significant rainfall and winters with very little • Cyclones: large rotating storm systems of low pressure air with converging winds at the center. • 2 Types Cyclones: • Extratropical cyclones: occur where Polar and Ferrel Cells meet • Tropical Cyclones: form within a single atmospheric cell

11. How do cyclones form? • When moist wind gets drawn into a low pressure area, causing it to twist around on itself • Appear to rotate the “wrong” way with respect to the Coriolis effect • Low pressure pulling the wind into the pattern is stronger than the Coriolis Effect • Winds that get drawn in and provide the cyclone energy are pulled away from the Coriolis Effect. Imparts a backwards spin. • Cyclones help with the redistribution of heat that is important to all life on Earth