8.3 & 8.4 EARTH’S CLIMATE SYSTEM

THE SUN POWERSEARTH’S CLIMATE

• Climate System: complex set of components that interact with each other to produce Earth’s climate.

• Includes sun, air, land, liquid water and ice and living things

BALANCE OF ENERGY ON EARTH• Almost all energy on Earth comes from the Sun• The sun emits radiation:– ultraviolet (short wavelength, high energy) – Visible light– infrared (long wavelength, low energy)

How does Radiation Interact?• Can be absorbed: causing particles to gain

energy• Can be transmitted through the particle• Can be reflected off the particle

What Happens to the Sun’s energy?

• 30% of solar radiation is reflected back into space by the atmosphere, clouds, and Earth’s surface

• 70% is absorbed by the atmosphere, clouds, and Earth’s surface

• See page 326 in text

What happens to the absorbed energy?

• < 1% absorbed by plants to power photosynthesis

• Absorbed by rocks and water to heat up earth

• As Earth’s temperature increases, air above is heated

Balancing Earth’s Climate

• Earth absorbs suns energy and gains thermal energy• Earth emits lower-energy infrared radiation back out • Energy absorbed = energy radiated back 19% + 51% = 64% (indirectly) + 6% (directly)

Helps keep Earth’s global temperature fairly constant

Answer these in your book…1 If the Sun shines constantly on the Earth, why

doesn’t it keep warming up?

2 What would happen to the Earth’s temperature if– The amount of energy from the Sun stayed the

same but the amount radiated back from the Earth increased?

– The amount of energy from the Sun stayed the same but the amount radiated back decreased?

Latitude Affects Climate Too!

• Climates are warmest near the equator because the sun shines directly overhead

• Closer to the poles, the sun hits surface at an angle and is weaker

Extra Facts• Mercury has no atmosphere and is 450°C

during the day and -170°C at night• Venus’ atmosphere is 100 times more dense

than Earth’s causing its surface temperature to be 700°C.

• Mars has an atmosphere 100 times less dense than Earth’s, causing its surface to be

-63°CGOD made earth so perfect

COMPONENTS OF EARTH’S CLIMATE

• There are 4 main components to Earth’s climate system

1 THE ATMOSPHERE2 THE HYDROSPHERE3 THE LITHOSPHERE4 LIVING THINGS

1 THE ATMOSPHERE• mixture of gases 78% nitrogen 21% oxygen and 1% other

(ozone, CO2, hydrogen etc.)• Allows solar radiation to strike the earth’s surface• Can also absorb some thermal energy from Earth and reflect it

back to earth before it can go out into space. This is called the greenhouse effect.

OZONE• The ozone protects living things from the harmful effects of UV

rays• In 1970 scientists noticed the ozone layer over Antartica was

thinning• In the 1990’s a similar ozone “hole” began to form over the Arctic• Caused by human made CFC’s (chlorofluorocarbons) • In 1987 the governments around the world signed an agreement

in Montreal called the Montreal Protocol on Substances that deplete the ozone layer

• The ozone layer is beginning to recover and will take at least 50 more years to return to its original thickness

2 THE HYDROSPHEREThe hydrosphere is made up of all of the water on the earth in all of it’s different forms.

The Hydrosphere…cont’d• Large bodies of water absorb and store more thermal

energy than land and therefore warms and cools more slowly

• Land near bodies of water take longer to heat up during spring and longer to cool down during fall

• Regions down wind from bodies of water tend to get more snowfall. Air passing over absorbs moisture and then falls as snow as it reaches the colder air inland

The Hydrosphere…cont’d

• Ocean currents help distribute thermal energy concentrated at the equator towards the poles.

• great ocean conveyor: an overall circulatory pattern

The Great Ocean Conveyor

The Hydrosphere cont’d

• 2% of all Earth’s water is frozen

• Most of this ice is located at the poles

• Ice/snow reflect more thermal energy, adding to the reason

why these areas are so cold

The Lithosphere

• Is the Earth’s crust—it includes all rock, soil and minerals on land and under the oceans

• It absorbs solar energy and emits it back as lower energy

The Lithosphere—LAND FORMATIONS & CLIMATE ZONES

• Mountains and other land formations affect how air moves over an area

• As clouds blow over mountains they lose their moisture as rainfall on the windward side

• The leeward side receive little rain (rain shadow effect)

The Lithosphere—ALTITUDE & CLIMATE• higher altitudes have lower atmospheric pressure because

there is less air pushing down• Therefore, air from lower altitudes rises to high altitudes,

expands and cools down• mountain tops = cooler

Living Things• All organisms are part of the climate system• Plants and animals exchange gases in the atmosphere• Photosynthesis releases O2

• Cellular respiration releases CO2

• Animals release methane during digestion as do bacteria• The quantities of these gases change which affects climate by

their ability to absorb radiation

Homework:

Pg 329 2,6Pg 335 1, 4, 5, 6