CLIMATE AND CLIMATE CHANGE

WHAT CAUSES CLIMATE?

Climate: The average, year-after-year conditions of temperature, precipitation, winds and clouds in an area.

FACTORS AFFECTING TEMPERATURE

1. Latitude: Warmer near the equator because the sun’s rays are more direct

2. Altitude: Temperature decreases for every 1km increase in altitude.

3. Distance from large bodies of water: Oceans moderate temperatures on land because large bodies of water heat slower and cool slower.

4. Ocean currents: Ocean currents can bring warm or cold air to land.

FACTORS AFFECTING PRECIPITATION

o Prevailing Winds: Amount of water vapor in air mass influences

rainfall & snowfall. the amount of water vapor in the air depends on

where the wind came from (wind from oceans carry more water!)

Air masses can be warm, cool, dry or humid

o Mountain Ranges: When wind hit a mountain it rises, cools, condenses into vapor, forms clouds and releases precipitation.

THE SEASONS

SEASONS HAVE NOTHING TO DO WITH HOW FAR THE EARTH IS FROM THE SUN!

Earth is FARTHEST from the sun during the summer in the Northern Hemisphere.

SEASONS

Tilted Axis Seasons are caused by the tilt of Earth’s axis as it travels

around the sun. The axis always points in the same direction so half the year

it is pointed toward the sun and the other half year it points away from the sun.

Summer is warmer because of direct sun rays. Winter is colder because of indirect sun rays.

Direct Sun Rays

Indirect Sun Rays

CLIMATE REGIONS

Scientists classify climates according to 2 major factors: Temperature and precipitation

6 main climate regions: Tropical rainy, dry, temperate marine, temperate continental, polar, and highlands

THE TROPICS

Tropic wet: Rainforests Year round heat and heavy rain Lush green vegetation

Tropic wet and dry: Savannas (tropical grasslands) Distinct dry and rainy seasons Only a few trees here that can survive dry season

DRY CLIMATES

Deserts receive less than 25 cm. of rain per year

They can be hot or cold!

Only specialized plants (cactus) can survive the dryness and temperature extremes.

TEMPERATE MARINE CLIMATES

Found along the coasts of continents

Oceans moderate the temperature

Humid

Have mild winters

TEMPERATE CONTINENTAL CLIMATES

Not influenced by oceans

Have extremes of temperature

POLAR CLIMATES

Coldest climate region

Icecap: Climate region with avg. temperatures at or below freezing, and covered with ice and snow.

Tundra: climate region with short cool summers and bitterly cold winters (more life than in icecap)

Permafrost: Permanently frozen tundra soil

HIGHLANDS

Places with high altitudes

Temperature falls with increasing altitude so these regions are colder than those surrounding them.

Precipitation increases (air masses carrying moisture over highlands)

STUDYING CLIMATE CHANGE

Pollen: pollen (from bottom of lakes and inside earth) give us information about ancient plants and therefore ancient climates.

Tree rings: Trees grow a new layer of wood each summer and scientists study the pattern of rings and determine if previous years were warm, cool, wet or dry.

Cool climates: thickness of tree ring depends on length of warm growing season.

Dry climates: Thickness depends on amount of rainfall

CAUSES OF MAJOR CLIMATE CHANGE

1. Earth’s Position: Angle of Earth’s tilt and shape of orbit change slightly over time (may cause ice ages)

2. Solar Energy: Sunspots are dark, cooler regions on the sun’s surface, and they increase/decrease in 11-year cycles. When there are more sunspots the sun produces more energy (increase Earth’s temp.)

3. Volcanic Activity: Release of gas and ash block solar radiation and cool the planet.

4. Movement of Continents: These changes affect global patterns of winds and ocean currents, and therefore the climate.

SHORT TERM CLIMATE CHANGE

Changes in ocean currents and wind can greatly affect climate.

El Nino: Warm water event when unusual patterns of winds form over the western Pacific. Occurs every 2-7 years, changes weather patterns and can cause heavy rains or droughts for South America.

La Nina: Cold water event in Eastern Pacific that changes climate and brings colder winters, greater precipitation to USA, and more hurricanes.

GLOBAL WARMING

Most changes in climate occur naturally.

Recently, human activities have caused climate change.

Human activities have added greenhouse gases to the environment, trapping heat and making Earth warmer.

More carbon dioxide emissions (cars, planes, industries) causes more heat to be trapped.

Ozone layer is being destroyed by human activity (CFCs) and letting in harmful UV rays to Earth.