Specific Heat & Local Winds

Today’s Learning Outcome:

Students will be able to explain that the movement of air is due to the uneven heating of the Earth in order to model local wind patterns.

Wind

• Wind = differences in air pressure cause

the air to move

• The difference in air pressure is caused by

unequal heating of the Earth from the sun

The Sun is Earth’s heat source. The heat energy is transferred by radiation, conduction and convection. However, not all areas of Earth are heated evenly. The equator receives the most direct sunlight year-round and is also the hottest area on Earth. Depending on Earth’s tilt, certain areas/hemispheres will receive more or less direct light and therefore different amounts of heat.

​

Multiple Choice

Think back to learning about heat transfer...How does heat flow?

• Always from cold to warm

• Always from warm to cold

• Both warm to cold & cold to warm

• It depends on the temperature

​Temperature affects air pressure and density, causing air to sink or rise in specific areas

Temp
affects air
pressure

Uneven Heating of the Earth’s surface

causes Convection Currents which

causes differences in Pressure

which causes WINDS. Air always moves

from High to Low pressure areas.

Multiple Choice

Which of these causes wind on Earth?

• Sun and it warming Earth's atmosphere

• Sun and Moon

• Moon's gravity

• Potential Energy

Multiple Choice

When air particles gain energy and rise into the atmosphere, how does this affect the air pressure on the earth's surface?

• It causes the air pressure to rise creating high pressure.

• It does not affect the air pressure on the earth's surface.

• It causes 8th grade students to forget to do their homework.

• It causes the air pressure to drop creating low pressure

Multiple Choice

Cold air is less dense than warm air.

• True

• False

Multiple Choice

Why does warm air rise?

• Warm air is more dense than cooler air.

• Warm air has more pressure than cooler air.

• Warm air is less dense than cooler air.

• Warm air has a higher dew point than cooler air.

Multiple Choice

What would be the effect on the particles if more heat is supplied to the system?

• They would slow down

• They would stop moving

• They would speed up

• There would be no effect

Multiple Choice

Air moves from _______ pressure to ________ pressure.

• high to low

• low to high

• high to high

• low to low

​Imagine you are at the beach…Your toes felt nice and cool in the ocean on a summer day. Then, you decided to walk barefoot to the ice cream truck. The sand was much warmer than the ocean. The last part of the walk was the paved parking lot. Ouch! That black asphalt was hot.

​

Sand and asphalt, on the other hand, have lower specific heats. This means that their temperatures change more quickly. When the summer sun shines down on them, they quickly become hot. But, when the sun goes down, they also become colder more quickly. 

Water has a very high specific heat. That means it needs to absorb a lot of energy before its temperature changes. That is why it takes months for the water temperature to rise and fall at the beach with seasonal temperature changes.

Why, on the same day, are the temperatures of water,

sand, and asphalt so different? 

Specific heat is the key. Specific heat is how much heat energy is needed to raise the temperature of a substance.

Multiple Choice

Specific Heat is....

• The speed of the particles in a substance

• The temperature of the substance

• How much energy it takes to heat something up

• Heat

Multiple Choice

Why does water heat up and cool down VERY SLOWLY?

• High Specific Heat

• Low Specific Heat

• It's solid

• It's always cold

Multiple Choice

Land heats up and cools down faster than water.

• True

• False

Multiple Choice

A high specific heat means...

• It requires less energy to change temperature

• It requires more energy to change temperature

• It heats up very quickly

Local Winds

• Occur in small areas (Ex. = at the beach)
• Caused by unequal heating of surfaces (land vs water)

– water has a higher heat capacity than land (so it stays the

same temp day & night)

– Land has a lower heat capacity so it heats up and cools

down quickly

• Sea breezes occur during the day - it is when the wind comes from the sea (from colder area to warmer area)
• At night, flow of air comes from the land = Land breeze

Local Winds (are named for where the wind comes from)

• Day

• Night
Land is colder

Ocean is warmer

Ocean is colder

Land is warmer

wind

wind

Sea Breeze During The Day

Land Breeze At Night

Multiple Choice

How does the air move in a land breeze?

• From east to west

• From west to east

• From the land to the ocean

• From the ocean to the land

Multiple Choice

Is this a land or a sea breeze?

• land breeze

• sea breeze

Multiple Choice

In a sea breeze, the air is warmer above the _____.

• land

• ocean

• sky

• beach

Multiple Choice

Do sea breezes typically happen during the day or night?

• Day

• Night

Multiple Choice

Why do land breezes occur at night?

• Land cools off slower than water, so the air above water is cooler.

• Water cools off faster than land, so the air above land is warmer.

• Land heats up slower than water, so the air stays cooler during the day.

• Water cools off slower than land, so the air above water is warmer.

Multiple Choice

Is this a land or a sea breeze?

• land breeze

• sea breeze

Multiple Choice

Water is _______ than land during the day, causing a sea breeze.

• hotter

• larger

• cooler

• warmer

Multiple Choice

In which direction will air currents most likely move?

• from the land toward the sea

• from the sea toward the land

Multiple Choice

What type of heat transfer is responsible for sea breeze and land breeze?

• Conduction

• Convection

• Radiation

Multiple Choice

What causes wind to blow?

• Differences in longitude 

• Shock waves from clouds 

• Differences in air temperature and pressure 

• The rotation of the earth