Chapter: Atmosphere

Table of Contents

Section 3: Air Movement

We will learn about Air Movement=Wind

-Why different latitudes on Earth will receive

different amounts of Solar Energy

-The Coriolis Effect

-How water and land affect the air above them

Why it’s important:

Wind systems will affect weather and

climate all over the Earth

When substances

are mixed:

less dense will float

on the denser one

**different densities

cause convection

currents

**This is also valid

for the air in the

atmosphere and

water in the

hydrosphere

We know:

Air Density

• What happens to the molecules of a

substance when this substance is

warmed up?

• Does the density change?

The molecules or particles will expand

and the substance will become less dense

Density of gases depends on temperature

Higher temperature - lower density: air rises

Lower temperature – higher density: air sinks

*The density of the air affects Air Pressure

• Air Pressure – force exerted by the molecules

of air present in the atmosphere

• Read page 103 and write down on your

notebook how air density can affect air

pressure

*The density of the air affects Air Pressure

• In areas where the air is heated (less dense),

the air pressure is lower, because the

molecules are further apart from each other.

• In areas where the air is cold, the air

pressure is higher.

Air Movement – Wind

• What is wind?

• Wind is the movement of air from an area of higher pressure to an area of lower pressure

**Air Movement – Wind

• Earth surface has land and water

• Land and water - strongly influence global wind systems

• Land and water absorb heat differently, creating areas with different air pressure, generating wind

• Land and water absorb heat differently because of their specific heat

Heated Air

• Areas of Earth receive different amounts of radiation from the Sun because Earth is curved.

• some areas are warmer than others.

• areas closer to the Equator are warmer

Longitude and Latitudelatitudes closer to the Sun receive more

radiation and are warmer

How are Winds formed?

1)The heated air at

the equator is less

dense.

2)Moves up in the

atmosphere

3) It is replaced by

denser, colder air

from

the poles, creating

convection currents

*Forming Wind

The differences in air temperature and density, generate areas with different air pressures in the atmosphere, which creates all the winds that circulate around the globe.

How air moves

What causes wind?

1) As we have seen: the difference in

temperature and density of the air in

different areas, but also….

2) the “Coriolis Effect” – phenomenon that

also causes winds

*Coriolis Effect – Coriolis Effect happens

due to the rotation of the Earth.

It appears that winds and water are deflected

to the right in the Northern Hemisphere and

to the left in the Southern Hemisphere.

*Coriolis Effect

*It is a phenomenon that causes fluids

such as air and water to curve as they

travel across and above the Earth’s

surface, affecting how winds and storms

move around Earth and therefore the

climate and weather.

*Coriolis Effect

Coriolis Effect: Fun Fact

Specific Heat of Water

• Specific heat of the water will affect the movement of air.

• read page 659 and copy the definition of specific heat.

• Read page 659 and explain how the specific heat of water differs from the specific heat of many other substances

Local Winds: Sea and Land Breezes

• These breezes will blow in one direction during the day and to the opposite direction at night.

Sea and Land Breezes

*This constant air movement happens because of the differences in the temperatures and density of the air above land and water.

Sea and Land Breezes

• It takes more time for the water to cool down and warm up compared to the land (Sp. Heat), this affects the temperature and density of the air above it and the local wind patterns.

• Water has a high specificheat when compared to other substances

- Sea breeze – the cool air

- Land breeze – the cool air

• Global Winds – affect the weather

patterns of the entire planet

• Local Winds – affect local weather –

Sea breeze and Land breeze