What factors influence weather?

The water cycle, currents and air streams, layers of the

atmosphere.

Maine- Seasons• Maine has 4 distinct seasons.

• Spring lasts from March through June

• Summer is from June through August

• Fall is from September through November

• Winter is from December through February

Seasonal Variation• There is a huge variation in temperature based on season. Precipitation is constant.

Winter• Cold temp. (average below zero)• Precipitation comes as snow, ice

SpringWarming weather sparks growth, snow melts, precipitation switches to rain or sleet

Summer• Hot weather

(average temp. in the 30s)

• Precipitation comes as heavy rains

Fall• Cooling

temperatures• Storms often blow

up the coast• Plants pull sap back

into their roots, causing a change in color.

Why is this?

Indonesia - SeasonsWhile Maine has 4 seasons, Indonesia has only 2. The wet season runs from about November through April, while the dry season runs from May to October... or at least it used to.

Seasonal VariationThere is very little variation in temperature, but a huge seasonal variation in rainfall.

Why is this?

Review: The Water Cycle

Review: Climate ‘Cells’• Notice that each band of latitude has a cell, and these cells have different names.

• You need to know what actions (wind, rain) are taking place, but don’t worry about the names.

Maine - location• Maine is in the north east US and on the coast

• The weather is temperate, and it is under the updraft of the northern Ferrell Cell (rising air = lots of precipitation)

Indonesia- Location

Jakarta is in central Indonesia and on the coast.

The weather is tropical, but because cells shift, Jakarta is sometimes in the updraft of the tropical Hadley cells, and sometimes in the downdraft.

(Falling air = dry)

New Information: Wind Patterns

• Each cell has a wind flow pattern. These influence the weather.

Review: Climate Map

The same information in a different way:

These wind belts shift north between May and September, and south between October and April. What is the effect on Indonesia? What weather pattern does that explain?

Review: Land and Sea Breezes• Land heats and cools

faster than water. • The oceans (or large

lakes) act as ‘banks’ of both moisture and temperature.

• During the day, the sun warms the land. The hot air rises. Cool air from the sea flows over the land. At night, this reverses. Air over the land is cooler and over the sea is warmer… so sea air rises and land air flows out to sea.

Back to land masses…• Examine the top two maps.

• Remember what you know about seasonal wind patterns in Indonesia, and shore/sea breezes.

• What Asian weather pattern can we explain?

Ocean Currents: Surface• Remember the

flow of wind currents from earlier?

• Because winds at different bands of latitude go in opposite directions, ocean currents are circular.

Surface currents in the ocean are created by wind.

Ocean Currents: Deep• Deeper ocean

currents are created by differences in ocean temperature.

• Just like with atmospheric cells, warm water rises and cold water sinks.

• This creates ocean currents.

Effect on Climate• Land areas near warm ocean currents have warmer climates.

• Land areas near cold ocean currents have colder climates.

So that explains climate… what about weather?

• The same principles apply.

• Warm air rises, depositing moisture. Cool air sinks.

• Differences in surface area cause wind to flow from place to place.

Weather: High pressure systems

• High pressure is created when cooling air falls back to earth.

• Air is pushed out of the way by the cool, dry air, creating wind.

• There is no moisture in the falling air, so weather is clear and cool.

• High pressure systems are fair weather systems

Weather continued: Low Pressure Systems

• Low pressure is created when warm air rises. This causes rain, as the moisture condenses out.

• Nearby air fills in the gap left by warm rising air. This causes wind.

• Low pressure systems are storm systems.

What happens as warm air

rises?• The types of storms and

clouds that we see are created by what happens to warm, wet air as it rises.

• These effects have to do with the motion of air at the surface of the earth, but also the conditions of the atmosphere.

Layers of the Atmosphere

• Only the first few layers of the atmosphere contain weather

Storm Clouds• You can tell what weather is coming from the shape of clouds.

http://www.wikihow.com/Forecast-the-Weather-Using-Clouds