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Weather and Climate

• Weather – atmospheric conditions over a short period of time (day), studied by meteorologists.

• Climate – atmospheric conditions over a long period of time (months and years), studied by climatologists.

• Of main interest is precipitation and temperature.

Identify the factors that affect climate

and explain how each

affects climate.

Low Latitudes: Between the tropic of Cancer and Tropic of Capricorn, warm hot climates

North or South of the Equator makes a difference on the temperature and the wind patterns

High Latitudes: Warm when the poles are tilted towards the sun and Cool when the poles are tilted away from the sun

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THE EARTH’S AXIS - Seasons

The earth’s axis is tilted from the vertical by 23 ½ degrees.

The earth's orbit and tilt

A common misconception is that the seasons are caused by how far the earth is from the sun.

In Canada, we are actually closer to the sun in the winter time by about 900 000 kilometers.

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As we move from December to June the number of daylight hours increases due to the tilt of the axis (earth surface receives more direct sunlight). June to December daylight hours get shorter earth cools.

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Summer – Energy more intense

Winter – Energy less intense

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How does latitude affect climate?

As latitude ________, the averageannual temperature _________.

0° Latitude 90°

Tem

per

atu

redecreases

increases

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How does closeness to a large body of water affect climate?

Water __________ the temperature._______ summers. _______ winters.

City B is closer to a large body of water.

Its temperature line is flatter (moderated).

moderates

Cities A & B are located at the same latitude.

Cooler Warmer

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Washington DC - Man made body of water. Why?

The windward sides of the Adirondacks & Catskills receive a great deal more

precipitation

The leeward sides of the

Adirondacks & Catskills

receive much less

precipitation

How does the Orographic Effect

affect climate?

Windward Side: ___________Leeward Side: _____________

cool, moistwarm, dry

Temperature drop of 1ºC for each 100 m of elevation.

We live in the troposphere. Temperature decreases

with elevation.

During summer, temperature is strongly controlled by elevation -- cold at the higher reaches of the Alaska and Brooks Ranges, and warmer in the lowlands.

How does elevation affect climate?

As elevation _________, the averageannual temperature __________.

Elevation

Tem

per

atu

reincreases

decreases

• Water covers 70% of the earth’s surface.

• Water has a high heat capacity.• Water serves as a reservoir of

heat.• Ocean currents distribute the

absorbed heat around the world.

• The primary forces for surface ocean currents are:

• 1. Solar Heating

• 2. Winds

• 3. Gravity

• 4. Coriolis Effect

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• Ocean currents enable the flow of energy from the tropics to polar regions and back.

• Large ocean currents are constrained by the continental masses found bordering the three oceanic basins. Continental borders cause these currents to develop an almost closed

circular pattern called a gyre.

How do ocean currentsaffect climate?

Warm Currents: warmer climateCold Currents: cooler climate

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Wind CurrentsWINDS

Winds are due to the relationship between air temperature and air density.

Changes in air pressure cause movement of air.

Movement of air is called WIND.

Global Winds

The jet stream are high speed winds which travel all around the earth. They form at the boundary between cold air and warm air masses.

Cool air masses move towards the equator.

Warm air masses move towards the poles

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Upward movement - air lifts off the surface as the air is heated. This creates an area of low pressure.

Downward movement -there is a piling up effect. This creates an area of high pressure.

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Carioles Effect change of direction due to rotation

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A cold front occurs when a more dense air mass pushes

under a less dense air mass.

cumulusnimbus(rain)

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cumulonimbus cumulus

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A warm front occurs when a less dense air mass rides up

over a more dense air mass.

Stratus (layer)

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Cirrus Stratus