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CHAPTER 2

VARIABLE WEATHER AND CHANGING CLIMATE

A Continuing Challenge?

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CHAPTER 2 VARIABLE WEATHER AND CHANGING CLIMATEA Continuing Challenge?

In this Chapter you will explore three key questions:

1.Why do different places experience different weather and climate?

2.What is happening to the earth’s climate?

3.Is the weather becoming more extreme?

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RECAPITULATION FOR LESSON 1

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Recapitulation a. What is the difference between weather and climate?

Weather: Condition of atmosphere at a particular place and specific time.

Climate: Average condition of the atmosphere of a particular place over a long period of time, usually 30 years.

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Gateway 1: Why do different places experience different weather and climate?a. What is the difference between weather and climate?

b. What are the elements of weather?

c. What are the climatic types and where are they experienced?

CHAPTER 2 VARIABLE WEATHER AND CHANGING CLIMATE

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Gateway 1: Why do different places experience different weather and climate?

a. What is the difference between weather and climate?

b. What are the elements of weather?

-Temperature, relative humidity, clouds, rainfall, air pressure and wind.

c. What are the climatic types and where are they experienced?

CHAPTER 3VARIABLE WEATHER AND CHANGING CLIMATE

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b. What are the elements of weather?Temperature

• Temperature: Degree of hotness or coldness of a place.

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b. What are the elements of weather?Temperature

•Factors influencing temperatures at different locations.

- Latitude- Altitude- Distance from the sea- Cloud cover

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Factors influencing temperatures at different locations (LATITUDE)

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Factors influencing temperatures at different locations (LATITUDE)

• Latitude: Distance of any point on the earth measured north or south from the Equator.– Imaginary horizontal lines east to west of Equator.

– Equator is at a latitude of 0°North Pole is 90°N.South Pole is 90°S.

• Latitude is the most important factor affecting temperature!

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Factors influencing temperatures at different locations (LATITUDE)

North PoleLong, cold winters.Short, cool summers. Temperature range: -40 to 10°C

SingaporeSummer whole year round.Temperature range: 23 to 34°C

Factors influencing temperatures at different locations (LATITUDE)

The nearer the Equator, the higher the temperatures.

The further from the Equator, the lower the temperatures.

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b. What are the elements of weather?Temperature

•Factors influencing temperatures at different locations.

- Latitude- Altitude- Distance from the sea- Cloud cover

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Factors influencing temperatures at different locations (ALTITUDE)

• Altitude: Height of a place in relation to sealevel.

- General decrease of 6.5°C for every 1,000 m increase in altitude.

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Factors influencing temperatures at different locations (ALTITUDE)

How does altitude affect temperature?• Distance from surface of the earth

- Longwave radiation is heat emitted by the earth after absorbing shortwave radiation

- Most heat absorbed by the earth at lower altitudes -> little heat at high altitudes -> cooler

• Density of air- Air is less dense at higher altitudes -> absorb less long

wave radiation -> lower temperatures

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b. What are the elements of weather?Temperature

•Factors influencing temperatures at different locations.

- Latitude- Altitude- Distance from the sea- Cloud cover

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Factors influencing temperatures at different locations (DISTANCE FROM SEA)

LOCATION LATITUDE DISTANCE FROM SEA

TEMPERATURE RANGE

ANCHORAGE 61.1919° N 1 KM 20°CFAIRBANKS 64.8378° N 420KM 40°C

The sea heating and cooling more slowly than land influences the temperatures of

inland and coastal areas.

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Factors influencing temperatures at different locations (DISTANCE FROM SEA)

Maritime Effect: Effect large ocean bodies have onclimate of coastal areas.• Small temperature range• Cool summers and warm winters

Continental Effect: Effect huge land surfaces have on climate of inland areas.• Large temperature range• Hot summers and cold winters

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b. What are the elements of weather?Temperature

•Factors influencing temperatures at different locations.

- Latitude- Altitude- Distance from the sea- Cloud cover

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Factors influencing temperatures at different locations (CLOUD COVER)

• Cloud cover: Extent of sky covered by clouds- Higher amount of cloud cover results in smaller daily

temperature range

Do you know?

The average daily temperature range of the Sahara desert is 30°C? During very hot months, the temperature can be as high as 55°C in the day. Temperatures may also fall to below 0°C at night!

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Factors influencing temperatures at different locations (CLOUD COVER)

With cloud cover Without cloud cover

Day: Cooler-> Clouds reflect sun’s energy back to space.Night: Warmer-> Clouds prevent heat radiated from ground from escaping.

Day: Warmer-> Large amount of sun’s energy reaches earth’s surface.Night: Cooler-> Allows more heat radiated from ground to escape.

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Gateway 1: Why do different places experience different weather and climate?

a. What is the difference between weather and climate?

b. What are the elements of weather?

-Temperature, relative humidity, clouds, rainfall, air pressure and wind.

c. What are the climatic types and where are they experienced?

CHAPTER 3 RecapitulationVARIABLE WEATHER AND CHANGING CLIMATE