Weather and Climate

How does the Sun affect Earth’s atmosphere?

How does atmospheric pressure distribute energy?

How do global wind belts affect weather and climate? How do the ocean affect weather and climate?

The Sun and Latitude

• The Sun plays a major role in Earth’s weather and climate• Weather- the condition of the atmosphere at a given time

and place• Climate- weather conditions in a geographic region over a

long time• What happens to the Sun’s energy when is reaches Earth?

– Half is reflected back into space or absorbed by the atmosphere

– Earth’s surface absorbs the other half• Once absorbed, solar energy is converted into heat called

temperature

Greenhouse Effect

• Earth’s atmosphere traps heat energy

• The atmosphere allows much sunlight to pass through

• Earth’s air then slows the rate at which the heat escapes into space

• Greenhouse effect keeps the planet warm

Global Warming???

Atmospheric Pressure• Air in our atmosphere has weight• The air around you is always pushing on you– Force called atmospheric pressure

• Why is there less air pressure on a mountain???– The higher up you go the less air there is pushing

on you

High and Low Pressure• When air is heated is expands, becomes less

dense, and rises• This creates a low pressure area• Rising air cools, cool air may form clouds

which may bring rain• Low pressure usually accompanies unstable

weather conditions

• Cold air is dense and sinks toward the Earth’s surface

• Creates high pressure areas• As air sinks, it heats and dries• High pressure usually bring stable, clear, and

dry weather or extreme conditions• Four major air pressure zones: – Equatorial Low, subtropical highs, subpolar lows,

and polar highs– They carry air back and forth between the equator

and the poles

Global Wind Belts

• Air Pressure affects global wind patterns

• Wind always flows from high to low pressure areas

• Prevailing winds: winds that blow in the same direction most of the time

• Doldrums: Area where there are no prevailing winds and is calm, along the equator

• Middle Latitudes: Prevailing winds are called westerlies- flow from the west… Weather patterns go from west to east

• High Latitudes: Prevailing winds are called polar easterlies… Alaska is in the polar easterlies

• A front occurs when two air masses of very different temperatures or moisture levels meet

• Precipitation occurs at these fronts • Jet Streams: Prevailing winds in the upper

atmosphere… can reach more than 300 miles

Oceans and Currents• Oceans affect climate• Water heats and cools more slowly than land… land areas

near oceans do not have such great temperature ranges• Wind, rotation, and ocean temperatures create oceans

currents: flow in circular paths– Northern Hemisphere: Move clockwise– Southern Hemisphere: Move counterclockwise

• Currents move heat back and forth between the tropics and the polar regions

• Warm currents carry heated water toward the cooler latitudes

• Cool currents carry cooled water from middle latitudes toward the equator

Precipitation• Water vapor plays an important role in many

atmospheric processes• Evaporation: process by which water changes from a

liquid to a gas– Most vapor that turns into rain is evaporated from

the oceansAmount of water vapor in the air: humidity

Higher the temperature more water vapor the air can holdWhen air cools, it will reach a point where it can not hold water vaporCondensation then occurs: from gas to liquid stateIf big enough, condensation falls as precipitation

• Precipitation comes in four forms: – Rain, Snow, Sleet, Hail

• Precipitation is not evenly distributed around the world

• Highest in low pressure zones• Lowest in high pressure zones

Elevation and Mountain Effects

• High elevation affects weather and climate• Increase in elevation causes a drop in

temperature • Can be warm at bottom of mountain and

covered with snow or glaciers at the peak• Mountains influence climate through the

orographic effect

Orographic Effect

Storms

• Middle latitude storms may produce thunderstorms and tornadoes– United States experiences more tornadoes than any

other country• Tropics have different storms: Hurricanes are the

most powerful and destructive tropical cyclones – United States hurricanes usually form in the Atlantic

Ocean and move westward– Hurricanes in the Pacific Ocean are called typhoons

So lets watch some storms!!!

• http://dsc.discovery.com/videos/storm-chasers-highlights-season3/

Song or Skit!!!!!!• You will present!• Needs to be completely

informational yet entertaining• Also include bulleted notes to

coincide with your song/skit this can be done on butcher paper