World GeographyWorld Geography

Ch. 3 Weather & Climate Ch. 3 Weather & Climate

Earth’s Atmosphere & ClimatesEarth’s Atmosphere & Climates

The Sun plays the major role in The Sun plays the major role in Earth’s weather and climate. Earth’s weather and climate.

The four main attributes affecting The four main attributes affecting climate are: climate are: • the Sun the Sun • Atmospheric pressure Atmospheric pressure • Wind currents Wind currents • The ocean The ocean

Global Energy SystemsGlobal Energy Systems

Temperature – the measurement of Temperature – the measurement of heat energy. heat energy.

Greenhouse Effect – earth’s Greenhouse Effect – earth’s atmosphere allows sunlight to pass atmosphere allows sunlight to pass through it, but when the sunlight is through it, but when the sunlight is changed into heat energy it is changed into heat energy it is trapped by the atmosphere, and this trapped by the atmosphere, and this keeps the planet warm.keeps the planet warm.

SECTION 1

Factors Affecting ClimateFactors Affecting ClimateThe Sun’s Effect on Earth

The Sun’s energy reaches Earth

Half of the energy is reflected back into space or absorbed by the atmosphere.

The other half is absorbed by Earth’s surface and converted into heat energy.

The atmosphere traps this heat in a process called the greenhouse effect.

The greenhouse effect helps keep the planet warm.

Air Pressure & WindAir Pressure & Wind Air Pressure is the force of air around you Air Pressure is the force of air around you

extending from the top of the atmosphere that is extending from the top of the atmosphere that is constantly pushing on youconstantly pushing on you

Low Pressure Areas –bring unstable weather Low Pressure Areas –bring unstable weather conditions. conditions.

High Pressure Areas – bring stable, clear, dry High Pressure Areas – bring stable, clear, dry weather. weather.

All low-pressure centers are called cyclones. All low-pressure centers are called cyclones. Wind – is the horizontal flow of air. Wind – is the horizontal flow of air. Wind always flows from high to low pressure Wind always flows from high to low pressure

areas.areas.

Air Pressure & WindAir Pressure & Wind Air Pressure is the force of air around you Air Pressure is the force of air around you

extending from the top of the atmosphere that is extending from the top of the atmosphere that is constantly pushing on youconstantly pushing on you

Low Pressure Areas –bring unstable weather Low Pressure Areas –bring unstable weather conditions. conditions.

High Pressure Areas – bring stable, clear, dry High Pressure Areas – bring stable, clear, dry weather. weather.

All low-pressure centers are called cyclones. All low-pressure centers are called cyclones. Wind – is the horizontal flow of air. Wind – is the horizontal flow of air. Wind always flows from high to low pressure Wind always flows from high to low pressure

areas.areas.

4 major air pressure zones4 major air pressure zones

1.1. Equatorial low pressure – at the Equatorial low pressure – at the equator equator

2.2. Subtropical high pressure – equator Subtropical high pressure – equator to 30° N and equator to 30° S to 30° N and equator to 30° S

3.3. Subpolar low pressure – 30° N to Subpolar low pressure – 30° N to 60° N & 30° S to 60° S 60° N & 30° S to 60° S

4.4. Polar high pressure – 60° N to North Polar high pressure – 60° N to North Pole & 60° S to South PolePole & 60° S to South Pole

Wind SystemsWind Systems Prevailing Winds – Winds that usually blow Prevailing Winds – Winds that usually blow

from the same direction from the same direction • Trade Winds –blow from the subtropical high Trade Winds –blow from the subtropical high

pressure zone toward the equatorial low pressure zone toward the equatorial low pressure zone. There are NE and SE Trade pressure zone. There are NE and SE Trade Winds. Winds.

Doldrums – calm areas with no prevailing Doldrums – calm areas with no prevailing winds along the equator. winds along the equator.

Westerlies – West-to-East winds at Middle Westerlies – West-to-East winds at Middle Latitudes. Latitudes.

Polar Winds –mainly come from the east Polar Winds –mainly come from the east and occur at the poles.and occur at the poles.

Wind SystemsWind Systems

Front – two air masses with very Front – two air masses with very different temperatures and amounts different temperatures and amounts of moisture meet. Fronts usually of moisture meet. Fronts usually cause stormy weather. cause stormy weather.

Jet Stream – High speed westerly Jet Stream – High speed westerly moving winds in the upper moving winds in the upper atmosphere. Not felt directly, but atmosphere. Not felt directly, but they move major weather patterns.they move major weather patterns.

Ocean CirculationOcean Circulation

Ocean Currents – occur from the Ocean Currents – occur from the prevailing winds blowing across the prevailing winds blowing across the surface of the ocean surface of the ocean

Water & the AtmosphereWater & the Atmosphere

Evaporation – process where water is Evaporation – process where water is changed to gas changed to gas

Humidity – amount of water vapor in Humidity – amount of water vapor in the air the air

Condensation – process by which Condensation – process by which water vapor changes from a gas into water vapor changes from a gas into a liquid a liquid

Precipitation – Rain (condensed Precipitation – Rain (condensed droplets become large and fall)droplets become large and fall)

SECTION 2

Weather FactorsWeather Factors

Formation of Precipitation

rain snow sleet hail

Condensationclouds, dew, fog, frost

evaporation humidity

Elevation & TemperatureElevation & Temperature

Orographic Effect – Air comes off the Orographic Effect – Air comes off the ocean and hits the mountains. It is forced ocean and hits the mountains. It is forced to rise and it cools and condensation to rise and it cools and condensation begins. This results in rain or snow begins. This results in rain or snow

Rain Shadow Effect – Deserts form on the Rain Shadow Effect – Deserts form on the side of the mountain away from the wind, side of the mountain away from the wind, because areas in the rain shadow do not because areas in the rain shadow do not receive much rainreceive much rain

Orographic & Rain Shadow EffectOrographic & Rain Shadow Effect

The 12 types of climate regionsThe 12 types of climate regions Tropical humid Tropical humid Tropical wet and dry Tropical wet and dry Arid Arid Semiarid Semiarid Mediterranean Mediterranean Humid Subtropical Humid Subtropical Marine West Coast Marine West Coast Humid Continental Humid Continental Sub artic Sub artic Tundra Tundra Ice Cap Ice Cap HighlandHighland

SECTION 3 Climate and Climate and Vegetation Vegetation PatternsPatterns

Tropical humid climate

• close to equator • warm temperatures,

rainfall all year • receives Sun’s rays

directly all year • rising warm, unstable air • monsoons

Tropical wet and dry climates

• north and south of tropical humid • seasonal change in how Sun’s rays hit Earth • alternating wet and dry seasons • savannas