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Unformatted text preview: Continued notes…. • Temperature and salinity at the sea surface are determined by the net heat input and net freshwater input at the sea surface. • Net heating of the ocean --- warmer sea surface temp • Net cooling of the ocean --- cooler sea surface temp • Net evaporation ------- salty surface water • Net precipitation ------- fresher surface water Earth’s rotational axis is tilted by 23.5orelative to the plane of its orbit around the sun • The sun crosses the equator twice a year, and it moves between 23.5o S and 23.5 o N. • The seasons are caused by variations in the amount of incoming solar energy as Earth makes its annual rotation around the sun on an axis tilted by 23.5°. • During the Northern Hemisphere winter, the Southern Hemisphere is tilted toward the sun and the Northern Hemisphere receives less light and heat. • During the Northern Hemisphere summer, the situation is reversed. Sea surface temperature in Northern Hemisphere summer : • Warmer in the tropics (rarely above 30 degrees C). • Warmest in the western tropics except in the eastern Indian Ocean.* • Cooler in the polar region (near freezing temperature).* • Changes seasonally following the movement of the sun. *Surface salinity is determined by freshwater input at the sea surface. ITCZ – intertropical convergence zone – appears as a band of clouds near the equator. The position of the ITCZ shifts seasonally. It reaches its most northerly position in July and most southerly in January....
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- Spring '09