8U4L2 Convection Currents Intro

Convection Currents Intro

7.MS-ESS2-4. Develop a model to explain how the energy of the Sun and Earth’s gravity drive the cycling of water, including changes of state, as it moves through multiple pathways in Earth’s hydrosphere.

Open Ended

What do you SEE in this picture (single words, things you can point to!)

Open Ended

What do you NOTICE in this picture (What is happening in the picture? What is the picture trying to show you?)

Open Ended

What do you WONDER about this picture?

Convection currents cause the daily movement of clouds, wind, rain, and differences of air pressure

But HOW?

Let's see what we remember about HEAT!

Multiple Choice

When a liquid heats up it

• Evaporates into a gas

• Becomes a solid

• Lights on fire

• Freezes

Multiple Choice

How do molecules at warm temperatures differ from molecules at cool temperatures?

• At warm temperatures, molecules move around more and spread out.

• At warm temperatures, molecules grow in size.

• At warm temperatures, molecules exchange electrons more easily.

• At warm temperatures, molecules combine with each other more easily.

Multiple Choice

If these are all the same material, which one is likely the hottest?

When heat is added to a gas or liquid...

• The molecules move more

• The molecules move farther apart

• The material gets LESS DENSE

Warmer regions of fluid are less dense than cooler regions of fluid.

• Warmer regions RISE (go up) because they are less dense

• Cooler regions SINK (go down) because they are denser

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.

OK, hot air rises, cool air sinks, I knew that!

What else do I need to know?

Imagine you're at the beach late spring or early summer...

• It's a warm day outside

• You run toward the water...

Multiple Choice

Which part of the beach has warmed up the most from the sun?

• The top of the sand is much warmer

• The water is much warmer.

Multiple Choice

If the top of the sand gets warmer faster, then which heats up faster?

• The land

• The water

Water takes longer to heat up from the sun than the earth does. It also takes longer to cool down!

This is why the water is cool in the morning, and warm in the evening!

So, in the morning the land (and air above it) is warmer, and in the evening the water (and the air above it) is warmer!

Let's put these two ideas together!

Back to this picture...

Open Ended

What DIFFERENCES do you notice in the two pictures?

In the morning...

• The sun heats the land up faster!

• The land is warmer, heating the air above it, which makes it rise.

• The cool ocean air comes in to fill the low-pressure space left by the rising warm air.

• This creates a sea breeze (wind from the ocean) from the water to the land

In the evening...

• The sun is gone and the land has quickly cooled down. The ocean is still warm!

• The ocean heats the air above it, which makes it rise.

• The cool land air comes in to fill the low-pressure space left by the rising warm air.

• This creates a land breeze (wind from the land) from the land to the water

These movements create convection currents!

Multiple Choice

What causes wind?

• differences in air pressure

• differences in gravity

• difference in oxygen

• differences in the thermosphere

Multiple Choice

Which term is best described as the movement of air from land to sea?

• global winds
• sea breeze
• land breeze
• local winds

Multiple Choice

Where does the initial source of energy come from that creates winds?

• the moon
• the sun
• the Earth's surface
• the rotation of the Earth

Multiple Choice

Land and water absorb and release the sun’s heat in different ways. One result of this is a sea breeze. Which statement is true of sea breezes?

• They originate in the day and blow toward the land.
• They originate in the day and blow toward the water.
• They originate in the evening and blow toward the land.
• They originate in the evening and blow toward the water.

Multiple Choice

What kind of breeze is this & what time of day/night would it form?

• Land breeze - daytime
• Land breeze - nighttime
• Sea breeze - daytime
• Sea breeze - nighttime

What about where there is no water?

How is it windy there?

The same convection currents happen everywhere due to unequal heating of the earth.

Some things just heat up faster or have more sunlight hitting them!

Multiple Choice

Air is warmer and less dense at the equator because the equator receives more____________________.

• wind

• solar radiation

• air pressure

• condensation

Multiple Choice

What causes differences in air pressure?

• even heating of the Earth

• Even cooling of the earth

• uneven heating of the earth

• global warming

Convection Currents Vocabulary

• Aquifer - a layer of rock or sediment that stores water

• Evaporation - the process by which liquid water changes into water vapor

• Condensation - the process by which water vapor changes into liquid water, usually on a surface

• Groundwater - water stored below Earth’s surface

• Hydrologic Cycle - the repeating cycle of condensation and evaporation of water on Earth, causing clouds and precipitation

Convection Currents Vocabulary

• Infiltration - the process by which water on the ground surface enters the soil

• Precipitation - rain, snow, sleet, or hail that falls to the ground

• Runoff - excess water that drains away from land or buildings

• Sublimation - the process by which solid water changes into water vapor

• Transpiration - the process by which water travels through plants and releases as water vapor