WEATHER What causes weather Weather is a mix

WEATHER

What causes weather? � � � Weather is a mix of geography and atmosphere Land shape can strongly affect weather Weather can strongly affect the land shape

Sunny skies � The sun is responsible for heating the earth � Light � 174, 000 terawatts of solar energy reach the upper atmosphere per hour � All � takes 8 minutes 20 seconds to reach Earth of earth uses about 18 TWh of power Radiation breakdown: � 30% of the radiation is reflected by our atmosphere � About 20% is absorbed by clouds or atmosphere � About 50% reaches earth’s surface This is absorbed by land sea

Who turned out the lights? � Without the sun: � Earth’s temp would drop to -270º C � All liquid water would freeze � It would be pitch black (after 8 minutes) The light from other stars only provides 1/300 th the light of a full moon � Everything would die

Great big heater in the sky � We get constant heat from the sun � But � we get too much Our atmosphere blocks the extra radiation � Without the atmosphere: The earth’s average temp would drop to -15º C Your skin would instantly burn off Liquid water would evaporate � Why would the temperature drop, but everything burn?

Energy not warmth � � The sun radiates energy, not necessarily warmth Energy only heats if it is caught � The atmosphere captures the sun’s energy and traps it near Earth’s surface making heat � Burning or evaporation is caused by adding too much energy � Our atmosphere blocks most of the sun’s high energy and only lets safe levels in Radiation is also blocked by the magnetosphere

Earth’s coat � � Your body radiates energy Coats trap the energy next to your skin, making you warm Without the coat, the energy can just radiate away Without the atmosphere, all the energy hitting earth would be radiated away

Our big Greenhouse � The gases in the atmosphere trap the sun’s lower energy � Most common gases are N 2 (78%) and O 2 (21%) � CO 2 (. 03%) is most responsible for Earth warming � The atmosphere trapping the sun’s warmth is the Greenhouse effect � Having a greenhouse effect is good, it makes Earth’s surface temp survivable � Having too little of a greenhouse effect is bad, it makes Earth’s surface temp too cold � Having too much of a greenhouse effect is bad, it makes Earth’s surface temp too hot

Too much greenhouse � Adding CO 2 to the atmosphere increases greenhouse effect � Earth gets hotter � Added through industry, vehicle emissions (burning fossil fuels), deforestation, and farming � Why is more heat such a problem?

Normal weather cycle

Weather turned up!

Problems � Increased evaporation and heat means more wind � More � � wind = more storms, larger storms Melting glacial ice = more flooding More draught/wildfires = increased deforestation