Air Pressure adn Weather Notes and Questions

Air

Pressure

and

Weather

What is air pressure?

●

The weight of the air pushing down on the earth

●

Air has mass, so it affected by gravity

○

meaning the air/atmosphere is pulled down towards the earth

●

The surface (sea level) has the most air pressure -

○

it decrease as you increase in altitude

Why does air pressure matter?

● Changes in air pressure are driving force behind

changes in weather!

● Air moves from areas of higher pressure to areas of

lower pressure

● Movement of air creates changes in weather

Why don’t we ‘feel’ the pressure?

● Air pressure at sea level is about 14.5 pounds per square inch

● We don’t feel it because air in our body is exerting the same

amount of pressure outward - creating balance

● We CAN feel when pressure changes

What causes changes in air pressure?

●Warmer air is less dense and rises

○this creates areas of lower pressure

●

Cooler air is more dense and sinks

○

creating areas of higher pressure

●

Air near the ground heats and rises, then cools as it increases in
altitude and then sinks

●

This pattern creates convection currents in the air

Multiple Choice

Pressure is the effect of

• the weight of all the air above pressing down

• water vapor in the atmosphere

• greenhouse gases

• solar radiation

Multiple Choice

Gases that surround the Earth is called:

• Weather

• Atmosphere

• Air Pressure

• Climate

Multiple Choice

Air pressure________________ as altitude increases, due to the lower density of air molecules.

• stays the same

• increases

• never changes

• decreases

Multiple Choice

MORE dense air is found at:

• sea level

• higher altitudes

Multiple Choice

More dense air has ________ air pressure.

• LOW

• HIGH

Convection currents

Reorder

Reorder the following to demonstrate convection currents correctly. Start with the air being heated.

• Hot less dense air rises.

• New air moves in to replace the air that has moved out.

• Air cools as it moves further up

• Dense cool air returns to surface.

1

2

3

4

• 1
• 2
• 3
• 4

Weather is caused by...

● Uneven heating of the earth’s surface by the sun
● This unequal heating causes changes in how the atmosphere

‘behaves’ - it changes air pressure!

● There are many things that can cause uneven heating

​The angle that the light hits the surface of the earth causes uneven solar energy distribution. Due to the amount of light per surface area increasing at the equator and decreasing at the poles.

This helps to drive our convection currents in the atmosphere.

Multiple Choice

Sunlight hits the Earth at an angle. As a result of the tilt of the Earth, some areas of the Earth receive more direct sunlight than others, which means they receive more solar energy.

Which statement correctly describes how solar energy changes as latitude changes?

• The equator receives the least solar energy compared to any other latitude.

• The poles receive the most solar energy of all places on the Earth.

• Oceans and lakes receive more solar energy than land masses.

• Lower latitudes receive more solar energy than higher latitudes.

Match

Match the following

• Arrow 1

  Type of pressure?

• Arrow 3

  Type of pressure?

• Arrow 1

  Air Temp.

• Arrow 3

  Air Temp.

Low Pressure

High Pressure

Warm Air

Cold Air

• Low Pressure

• High Pressure

• Warm Air

• Cold Air

Things that affect heating: Albedo

Surface
type

Albedo
Measurement
Percentage
reflected (avg.)

Ice

35-50%

Forest

10-25%

Desert

28%

Water

5%

Urban

25%

Crops

20%

Clouds

50-70%

Snow

60-80%

Albedo: The amount of radiation reflected from different earth surfaces

Multiple Choice

What type of surfaces tends to reflect the most light radiation?

• Urban

• Water

• Snow

• Forest

Multiple Choice

What type of surfaces tends to absorb the most light radiation (not reflect)?

• Urban

• Water

• Snow

• Forest

Open Ended

How do you think a higher albedo has an effect on average temperatures for an area?

Audio Response

Look at the data table showing the difference in temperature on a cloudy day and a clear day. Make 2 conclusions about cloud cover and temperature based on the data

Open Audio Recorder

Audio Response

Look at the data table showing the difference in temperature on land (soil) and over water. Make 2 conclusions about how surface type (land vs. water) affects temperature based on the data.

Open Audio Recorder

High and Low pressure systems and weather

High-pressure areas are shown with an

Low-pressure areas are shown with an

High Pressure Systems

●

As air COOLS it becomes more dense and sinks -
exerting more pressure at the surface (HIGH)

●

High pressure systems are sinking air
○

generally cooler than the surrounding air

●

Associated with ‘nice’ weather
○

sunny and dry

●

Air moves outward from the high pressure center

Low pressure

● As air warms, air molecules spread out and rise

○ This exerts less pressure (LOW)

● Warmer air can hold MORE moisture
● Low pressure systems associated with rain, cloudy

weather, but usually warmer air (compared to
surrounding air masses)

● Air moves IN towards the center of the low

Multiple Choice

High pressure is

• cool sinking air

• warm rising air

Multiple Choice

What type of air pressure is present?

• High 

• Low

Multiple Choice

Low pressure is

• cool sinking air

• warm rising air

Multiple Choice

Which pressure system is associated with clear skies?

• High Pressure

• Low Pressure

Multiple Choice

High Pressure is associated with this type of weather...

• Cloudy/Overcast Weather

• Cold Weather

• Warm Weather

• Fair Weather

Multiple Choice

Precipitation and storms occur ____.

• in high-pressure systems

• in polar zones

• in low-pressure systems

• at fronts

Air Pressure and Wind

● Air moves from areas of high pressure to low pressure

● Moving air is WIND
● Watch this video

Multiple Choice

Which statement best describes the general movement of air masses?

• They move from areas of high altitude to areas of low altitude.

• B.They move from areas of high pressure to areas of low pressure.

• They move from areas of high humidity to areas of low humidity

• They move from areas of low temperature to areas of high temperature.

Multiple Choice

The Coriolis Effect is caused by what?

• The wind blowing

• Earth's gravity pulling things down

• The rotation of the Earth

• The pull of the Moon

Multiple Choice

Winds blow from areas of what to what?

• High temperature to high pressure

• Low temperature to high pressure

• High pressure to low temperature

• Low temperature to high temperature

Multiple Choice

what is the coriolis effect?

• change in location of warm and cold surface water every 2-7 years

• tendency of objects moving large distances on Earth’s surface to bend to the right in the northern hemisphere & to the left in the southern hemisphere

• winds in northern Indian ocean that blow from the southwest in the summer & from the northeast in winter

• two layers of horizontal winds moving in opposite directions

Multiple Choice

Which statement best describes the movement of winds?

• Winds blow from low-pressure to high-pressure regions.

• Winds blow from high-pressure to low-pressure regions.

• Winds blow from north to south.

• Winds blow from east to west.

Video Response

Describe the role that convection currents, albedo (reflectiveness) and air pressure play in causing our weather.

Open Video Recorder