World Geography Ch. 3 Weather & Climate

Earth’s Atmosphere & Climates The Sun plays the major role in Earth’s weather and climate. The Sun plays the major role in Earth’s weather and climate. The four main attributes affecting climate are: The four main attributes affecting climate are: the Sunthe Sun Atmospheric pressureAtmospheric pressure Wind currentsWind currents The oceanThe ocean

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

SECTION 1 Factors Affecting Climate The 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 & Wind Air Pressure is the force of air around you extending from the top of the atmosphere that is constantly pushing on you Air Pressure is the force of air around you extending from the top of the atmosphere that is constantly pushing on you Low Pressure Areas –bring unstable weather conditions. Low Pressure Areas –bring unstable weather conditions. High Pressure Areas – bring stable, clear, dry weather. High Pressure Areas – bring stable, clear, dry 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 areas. Wind always flows from high to low pressure areas.

Air Pressure & Wind Air Pressure is the force of air around you extending from the top of the atmosphere that is constantly pushing on you Air Pressure is the force of air around you extending from the top of the atmosphere that is constantly pushing on you Low Pressure Areas –bring unstable weather conditions. Low Pressure Areas –bring unstable weather conditions. High Pressure Areas – bring stable, clear, dry weather. High Pressure Areas – bring stable, clear, dry 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 areas. Wind always flows from high to low pressure areas.

4 major air pressure zones 1. Equatorial low pressure – at the equator 2. Subtropical high pressure – equator to 30° N and equator to 30° S 3. Subpolar low pressure – 30° N to 60° N & 30° S to 60° S 4. Polar high pressure – 60° N to North Pole & 60° S to South Pole

Wind Systems Prevailing Winds – Winds that usually blow from the same direction Prevailing Winds – Winds that usually blow from the same direction Trade Winds –blow from the subtropical high pressure zone toward the equatorial low pressure zone. There are NE and SE Trade Winds.Trade Winds –blow from the subtropical high pressure zone toward the equatorial low pressure zone. There are NE and SE Trade Winds. Doldrums – calm areas with no prevailing winds along the equator. Doldrums – calm areas with no prevailing winds along the equator. Westerlies – West-to-East winds at Middle Latitudes. Westerlies – West-to-East winds at Middle Latitudes. Polar Winds –mainly come from the east and occur at the poles. Polar Winds –mainly come from the east and occur at the poles.

Wind Systems Front – two air masses with very different temperatures and amounts of moisture meet. Fronts usually cause stormy weather. Front – two air masses with very different temperatures and amounts of moisture meet. Fronts usually cause stormy weather. Jet Stream – High speed westerly moving winds in the upper atmosphere. Not felt directly, but they move major weather patterns. Jet Stream – High speed westerly moving winds in the upper atmosphere. Not felt directly, but they move major weather patterns.

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

Water & the Atmosphere Evaporation – process where water is changed to gas Evaporation – process where water is changed to gas Humidity – amount of water vapor in the air Humidity – amount of water vapor in the air Condensation – process by which water vapor changes from a gas into a liquid Condensation – process by which water vapor changes from a gas into a liquid Precipitation – Rain (condensed droplets become large and fall) Precipitation – Rain (condensed droplets become large and fall)

SECTION 2 Weather Factors Formation of Precipitation rainsnowsleethail Condensation clouds, dew, fog, frost evaporationhumidity

Elevation & Temperature Orographic Effect – Air comes off the ocean and hits the mountains. It is forced to rise and it cools and condensation begins. This results in rain or snow Orographic Effect – Air comes off the ocean and hits the mountains. It is forced to rise and it cools and condensation begins. This results in rain or snow Rain Shadow Effect – Deserts form on the side of the mountain away from the wind, because areas in the rain shadow do not receive much rain Rain Shadow Effect – Deserts form on the side of the mountain away from the wind, because areas in the rain shadow do not receive much rain

Orographic & Rain Shadow Effect

The 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 Highland Highland

SECTION 3 Climate and Vegetation Patterns 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