Climate and The Ocean Chapter 17

Chapter 17 Objectives You will be able to: Describe how ocean temperatures affect weather and climate. Explain the difference between climate and weather Discuss what causes differences in temperature during the different seasons

Background Geology Earth has three major layers. The land “lithosphere” Core, mantle, crust The water “hydrosphere” The air “atmosphere” The different layers interact with one another to produce changes in each part. Wind makes waves. Evaporation of water forms clouds. Precipitation over land.

Weather Local, short term conditions in the atmosphere Humidity Temperature Wind velocity Varies from place to place and day to day

Climate Long term prevailing patterns of weather Characterizes large geographical areas Affected by the ocean

Earth’s Climate Is not uniform (not the same all around) Warmest at the equator Coldest at the poles Variation in temperature due to sun’s rays Angle the rays strike the surface Type of surface they hit If they are reflected or absorbed Time of year Earths position relative to the sun

Radiant Energy Energy from the sun Travels through space as “rays” (radiation) Sun emits different kinds (visible light, uv light, gamma rays) Some absorbed, some reflected.

Angle of Insolation The amount of solar (sun) energy that reaches any part of the planet depends on the angle that the rays hit earths surface. This is the angle of insolation

Solar Energy Solar energy most intense at the equator Rays are direct, striking the earth at an angle of 90° Regions North and South of the equator receive rays at an slanted angle Slanted rays are spread out over a larger area than direct rays, therefore they are less intense.

Ocean Temperature Ocean temperature varies with latitude Warmest at the equator Generally, as the distance North or South of the equator increases, temperature decreases (not considering ocean currents) Due to the angle of insolation

Ocean Temperature Ocean temperature also varies by season The axis of earth has a tilt, or angle of inclination of 23.5 degrees from vertical in relation to the sun.

Seasonal Variations in Ocean Temperature: Northern Summer In the Northern Hemisphere during summer (begins June 21) earth is tilted toward the sun. Northern oceans warm because the suns rays strike directly during this time.

Seasonal Variations in Ocean Temperature: Northern Winter In the Winter (begins December 21) the northern hemisphere is tilted away from the sun. Slanted rays deliver less intense heat, so the northern oceans cool.

What about the Southern Hemisphere? Because of the earths tilt, summer and winter seasons are reversed in the Southern Hemisphere!

Land vs. Water The sun’s rays can penetrate farther into the water than land, because water is transparent. The depth depends on the rays energy. Most solar radiation absorbed within top 60 meters. Some penetrates hundreds of meters.

Ocean Wind Sea breezes and land breezes are convection currents. During the day the sun heats the sand, causing hot air to rise above it; cooler air over the ocean flows in to take its place, causing a sea breeze.

Ocean Wind During the night, cooler air over the land flows out, as a land breeze, to take the place of warmer air that rises above the ocean.

Coastal Temperatures Temperatures along the coast are generally more moderate than inland areas. During the summer the ocean has a cooling effect on coastal cities. During the winter the ocean has a warming effect.