Wild about

Weather

Weather is the current atmospheric conditions, such as air

temperature, wind speed, wind direction, cloud cover,

precipitation, relative humidity, air pressure, etc.

8.10B: global patterns of atmospheric movement influence local weather using

maps that show high, low pressures and fronts

8.10C identify the role of oceans in the formation of weather systems such as

hurricanes

Change the way you think

• In order to understand weather, you need

to start thinking vertically!

• For example – air moving parallel to the

ground is called wind, while air moving up

and down is called a current

Change the way you think

• Heated air rises, while cooler air sinks (the

same with water)

• The motion of air in the atmosphere above

our heads (vertically) plays a large part in the

weather we experience here at earth’s

surface.

Climate vs. Weather

• Weather is daily changes in the

atmosphere, which includes temperature,

wind, humidity, etc.

• The average weather in an area is the

climate for that area

• For example: The weather in Austin Texas

on June 5th is 950 and warm, but the

climate for the area during summer is hot

and dry

Oceans and Climate

How does the ocean affect our climate?

• The ocean is an important factor in global

climate because it collects and moves water,

heat and carbon dioxide.

– These components are constantly exchanged

between the atmosphere and the hydrosphere (water

on earth)

– Ex. water is evaporated from the hydrosphere to the

atmosphere

• The oceans can store a lot of heat. When the

ocean waters are warm, so is the air above it.

Weather Patterns – why all of this happens…

Changes in the weather patterns occur as the earth tries to equalize the temperature. The equalization comes from

• Global Wind Currents

• Global Ocean Currents

•An air mass is a large

body of air that has

similar temperature

and moisture

properties

There are two ways to identify air masses. You can identify air masses by the amount of : moisture and temperature they have

Using Moisture to identify air masses:

–Continental (c) -Located over large land masses - DRY

–Maritime (m) -Located over the oceans - HUMID

Using temperature to

identify air masses:

–Polar (P) - Cooler

–Tropical (T) - Warmer

Moisture and temperature are then combined to describe the air mass

–cT –

– cP –

– mT –

– mP –

Dry cold

Dry warm

Humid warm

Humid cold

Put together on a map:

30o Latitude

Tropic of

Capricorn

Fronts• A front is the front edge of

the boundary between air masses that have different characteristics.

• There are 4 different types of fronts

– Cold Front

– Warm Front

– Stationary Front

– Occluded Front

Cold Front• The cold dense air behind a cold front

pushes the warmer air up forming

cumulus clouds

• A cold front usually moves fast and

causes showers and thunderstorms

• The weather after the front is colder

but dry and sunny

Add to your page!

Cold Front

Warm Front• The warm air behind a warm front pushes over

the cooler air ahead of it forming stratus clouds

• A warm front causes steady rain, drizzle and fog. The clouds are slow to build, and the rain lasts longer

• After the front passes, the temperatures rise and it is more humid.

http://www.classzone.com/books/earth_science/terc/content/visualizations/es2002/es2002page01.cfm?chapter_no=visualization

Stationary Front

• A stationary front occurs when a

cold front and a warm front meet

up, but neither moves out of the

way

• The air is unsteady and sometimes

causes rain, and showers

Stationary Front – Going Nowhere

• As the name implies, a stationary front doesn’t

move (for a while).

• If the stationary front produces rain, then the rain

continues to fall until the front does finally move.

• This type of front can lead to flooding (just as we

saw a few summers ago).

Occluded Front• An occluded front occurs when two cooler

air masses merge, forcing warmer air to rise between them

• An occluded front usually brings dry air. Weather similar to a warm front

What are “pressure systems”?

• Again, think “vertically.”

• Basically, air cools as it rises, which can cause

water vapor in the air to condense into liquid

water droplets, sometimes forming clouds and

precipitation.

• On the other hand, sinking air is associated

with warming and drying conditions.

• So the first important point to keep in mind is

rising air = moistening, sinking air = drying.

Pressure SystemsDraw these in your notes!

Leave room underneath these two to add information!

Pressure Systems - High

• Higher density air sinks

• Pressure gets higher

• Winds go clockwise

(draw arrows in your

box)

• Good weather

• Few clouds, no rain

Pressure Systems - Low

• Low density air rises, then

cools.

• When it cools, water vapor

condenses and forms

clouds

• Winds go counter-

clockwise

• means stormy weather,

clouds and rain

Online Weather Exploration