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”

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.