The Movement of AIR6.9B verify through investigations that thermal energy moves in a predictable pattern from warmer to cooler 6.5B recognize that a limited number of elements comprise the largest portion of oceans and atmosphere8.10A recognize that the Sun provides the energy that drives convection within the atmosphere and oceans, producing winds and ocean currents

Notes and Stations Page2

Recall from “Heat on Earth” Lesson:

•Sun heats the earth unevenly

• Land and water heat the air

•Temperature differences cause pressure differences

•Air travels in circular patterns called convection cells (cells are small convection currents)

•High pressure moves to low pressure

Atmosphere on earth

The atmosphere

• The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.

A. It is mainly composed of a few limited elements:

• Nitrogen ~78%

• Oxygen ~21%

• Argon, Carbon, Neon, Helium, Hydrogen, & Krypton ~1%

The Atmosphere

B. It is a complex and dynamical, physical and chemical system.

• Dynamical: the processes of evaporation, condensation, precipitation

• Physical: the transfer of heat from the Sun to the Earth’s surface

• Chemical: the transformation and production of gases, such as ozone through chemical reactions of atmospheric gases.

Layers of the Atmosphere

• The troposphere is the atmospheric layer closest to the planet and contains the largest percentage (around 80%) of the mass of the total atmosphere.

• All weather phenomena occur within the troposphere

What is Wind?

•Movement of air is caused by temperature or pressure differences•Wind is the movement of air as a result of different air pressure• The greater the pressure difference, the stronger the wind

How and why wind moves• Wind (air) always moves from high pressure to low pressure (this

key, remember it!!!)

• Air moves because of an imbalance in the forces acting on the air molecules.

• Wind is the atmosphere's way of trying to bring the interaction of these forces into a balance; an equilibrium.

• Due to uneven heating of Earth and the differences in how the atmosphere heats versus how the land and water heat – this imbalance is constantly changing so the balance is never achieved and the air molecules move, which is wind.

Wind Speed

•Wind also blows faster if there's nothing in its way, so winds are usually stronger over oceans or flat ground.

Trees and other large objects can block and/or slow the wind’s speed

Wind Direction

• Although wind blows from areas of high pressure to areas of low pressure, wind doesn't blow in a straight line.

• That's because the earth is rotating. In the northern hemisphere, the spin of the earth causes winds to curve to the right (to the left in the southern hemisphere).

• This is called the Coriolis effect.

Stations Work

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Stations

• Station A – Exploring Wind

• Station B – Air pressure

• Station C – Coriolis and Jet stream

• Station D – Types of Wind (Local and global)

Station A – Exploring Wind - Wind Map

• Inquiry Question: How does wind move?

• Watch the wind move today!

• http://hint.fm/wind/

Station A – Wind Diagram

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Station A – Tools to measure Wind

• Meteorologists can forecast the speed and direction of wind by measuring air pressure with a barometer.

• Go to link to find equipment used to measure wind (posted on website)

• http://www.weatherwizkids.com/?page_id=82

• Find information on the weather instruments listed on your student page.

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Station A - Measuring the wind

Follow the directions on how to use the anemometer and the fan:

• Turn on the fan on the lowest setting and observe how fast it spins when the wind speed changes

• To see the changes, you may have to speed up the fan

• Now set up the fan on one side of the room and mark a line with tape on the other side of the room from the fan, about 6–8 steps away.

• Turn the fan on low speed (#1 on the fan) and stand on the line across the room. Hold up your anemometer and count the number of turns it makes in a minute. This is its revolutions per minute (RPM). Get someone to help you time the minute with a phone so that you can do the counting.

• Fill in the data table on your page for each wind speed.

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Station B – Air PressureInquiry Question: What is air pressure/atmospheric pressure?

• The air around you has weight, and it presses against everything it touches.

• That pressure is called barometric pressure, or air pressure.

• It is the force exerted on a surface by the air above it as gravity pulls it to Earth.

• pressure = amount of force/area

Station B – Air Pressure Key idea: Temperature differences cause pressure differences

• Air temperature is generally higher at ground level due to heating by the Sun of the land

• Temperature generally decreases with increasing altitude.

• In cold air, the molecules are more closely packed together than in warm air, so cold air is more dense than warm air.

• The higher density in a mass of air , the higher the pressure.

Station B – Air Pressure

Key Idea: High pressure moves to low pressure

• However, air lower in the atmosphere (closer to Earth) is more dense than air above, so air pressure down low is greater than air pressure higher up.

• Since warm air is less dense and creates less air pressure, it will rise; cold air is denser and creates greater air pressure, and so it will sink (go down).

Station B – Air pressure

• When warm air rises, cooler air will often move in to replace it, so wind often moves from areas where it's colder to areas where it's warmer.

• The greater the difference between the high and low pressure or the shorter the distance between the high and low pressure areas, the faster the wind will blow.

• Watch the video called “Air and Air Pressure” (link is posted on website)

Station C – Coriolis Effect and Jet Stream

Inquiry Question: What is the Coriolis Effect?

• If the Earth was not rotating, winds would move in a straight line

• However, winds are deflected or curved due to Earth’s rotation

• The invisible force that appears to curve the wind is the Coriolis force.

• The Coriolis force is strongest near the poles, and absent at the Equator.

• The key to the Coriolis effect lies in the Earth’s rotation. Specifically, the Earth rotates faster at the Equator than it does at the poles.

• In the Northern hemisphere, air moving north curves east and air moving south curves to the west

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Station C – Coriolis Effect Diagram

• Fill in the two missing circles on your diagram

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Coriolis Effect –Diagram - Check

• The difference in the speed of rotation causes the Coriolis Effect

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How The earth turns – the Coriolis effect

Station C – Jet Stream

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» A high altitude wind, about 7-16 km up (that’s roughly 6-9 miles high)

» Airplanes fly at 35,000 feet or about 6 miles up» These are narrow belts of high speed winds

that blow from west to east» If a pilot can use the jet stream to travel, they

save on fuel and can go faster» Two jet streams, polar and subtropical

The Jet Streams

Station D – Types of Wind

• Inquiry Question: How do the types of wind differ?

• Fill in the graphic organizer

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Earth’s Winds

Local Winds Global Winds

Sea Breeze Land Breeze Trade Winds Westerlies Easterlies

Station D – Types of Wind

• Texas Gateway link: https://www.texasgateway.org/resource/sun-and-convection-currents (posted on website)

• Scroll down until you are in the section titled “Types of Wind”

• Fill in the graphic organizer and diagrams on your page using this link.

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