Climate & Biomes

Weather Short term day to day changes in temperature, air pressure, humidity, precipitation, cloud cover, & wind speed Result of uneven heating & rotation of the Earth

Changes in weather when: Air masses meet Air mass: large area of air with similar temperature & moisture level throughout Cold front  stationary warm front – Result: thunderstorms & heavy rains Warm front  stationary cold front – Result: steady rain

Changes in weather due to: Changes in atmospheric pressure High pressure – Air descends from the center = dry weather Low pressure – Air ascends from center, cools = rainfall

Weather Vs. Climate

Climate Long term average precipitation & temperature of a particular area (30 years) Determined by: – Latitude – Wind patterns – Ocean currents – Altitude – Topography

Latitude Distance from the equator Uneven heating of the Earth’s surface causes change in temperature Cold Cool Temperate Warm Temperate Tropical (equator) Tropical Warm Temperate Cool Temperate Cold Lower Latitude Near the equator No season – high temps Higher Latitude Near Poles Seasons – Temps vary

Fall (sun aims directly at equator) Summer (northern hemisphere tilts toward sun) Spring (sun aims directly at equator) 23.5 ° Winter (northern hemisphere tilts away from sun) Solar radiation Fig. 6.5, p. 124

Wind Patterns Properties of air: – Hot air is less dense than cool air Hot rises, cold sinks – Warm air holds more water vapor As warm air cools, water is released Due to: – Uneven heating of the earth’s surface – Rotation of the earth on its axis – Properties of air, water, & land

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Rain Shadow Effect Most precipitation falls on windward side Deserts are found on leeward side

Coriolis Effect Earth’s rotation on its axis

Climate the average weather patterns for an area over a long period of time (30 - 1,000,000 years). is It is determined by Average Precipitation Average Temperatureand which are influenced by latitudealtitudeocean currents and affects where people livehow people live what they grow and eat Fig. 6.3, p. 123

Greenhouse Effect The rise in temperature the Earth experiences because certain gases in the atmosphere trap heat from the Sun’s rays

Importance of the Greenhouse Effect Without it, the Earth would not be warm enough to support life

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Greenhouse Gases Gases with the ability to trap heat 1.Water vapor 2.Carbon Dioxide 3.Nitrous Oxide 4.Methane

Water Vapor Biggest contributor to the “natural greenhouse effect Human activities have the least impact on water vapor’s prevalence in the atmosphere

Carbon Dioxide Most important greenhouse gas Influenced heavily by anthropogenic activities Responsible for 60% of the enhanced greenhouse effect

Nitrous Oxide Makes up small amount of the atmosphere – Less than 1/1000 th as abundant as CO 2 More effective at trapping heat – x more effective than CO 2

Methane Accounts for 20% of the enhanced greenhouse effect Leaves the atmosphere quicker than other greenhouse gases Major increases from livestock, agriculture, & land fills

Ocean Currents Affected by solar distribution Evaporation transfers energy to atmosphere & transports heat Upwelling: trade winds move surface waters away from land & outgoing water is replaced by nutrient rich bottom water

El Nino El Nino – Southern Oscillation Prevailing winds in tropical Pacific Ocean change direction Affects weather 1-2 years

Impacts of El Nino

El Nino in the US

El Nino Data

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