UNIT THREE: Matter, Energy, and Earth

Chapter 8 Matter and Temperature

Chapter 9 HeatChapter 10 Properties of MatterChapter 11 Earth’s Atmosphere and Weather

Chapter Eleven: Earth’s Atmosphereand Weather

11.1 Earth’s Atmosphere11.2 Weather Variables11.3 Weather Patterns

Investigation 11A

Key Question: How does solar radiation affect the heating

and cooling of continents and oceans?

Heating Land and Water

11.1 Learning Goals

Describe the composition of Earth’s atmosphere.

Explain the meaning of atmospheric pressure and describe how it is measured.

Identify the layers of Earth’s atmosphere and discuss unique characteristics of each layer.

11.1 The Atmosphere Earth’s atmosphere is a

layer of gases surrounding the planet, protecting and sustaining life. It insulates us so that we

don’t freeze at night. Its ozone layer protects us

from the sun’s ultraviolet rays.

It also contains the carbon dioxide needed by plants for photosynthesis, and the oxygen we need to breathe.

11.1 What's in Earth's atmosphere? This wonderful protective layer exists around

Earth because our planet has just the right balance of size and distance from the sun.

Nitrogen gas makes up about 78 percent of Earth’s atmosphere.

The second most abundant gas is oxygen, which makes up 21 percent of Earth’s atmosphere.

11.1 Nitrogen Cycle Nitrogen is

important to protein which is found in the body tissues of all living things.

Nitrogen is cycled through the soil and into plants and finally when living things die and decay.

11.1 Why is Earth different? The atmospheres of Venus, Earth, and Mars

were formed in similar ways, so we might expect them to contain similar elements.

Photosynthesis changed Earth’s atmosphere.

Photosynthesis and the atmosphere

Photosynthesis converts carbon dioxide to oxygen in a process that allows living things use the sun’s energy.

11.1 Earth stores carbon

Many marine organisms such as microscopic phytoplankton use carbon dioxide dissolved in seawater to form shells of calcium carbonate.

11.1 Atmospheric

pressure Atmospheric pressure is a measurement of the force due to air molecules at a given altitude.

The pressure of the atmosphere decreases as you rise above sea level.

11.1 Pressure changes with altitude

11.1 Atmospheric pressure At sea level, the weight

of the column of air above a person is about 9,800 newtons (2,200 pounds)!

This is equal to the weight of a small car.

Why aren’t we crushed by this pressure?

11.1 Measuring Pressure

11.1 Measuring PressureA barometer is an instrument that measures atmospheric pressure.

Long ago, mercury barometers were used.

11.1 Parts of an Aneroid Barometer

11.1 Layers of the

AtmosphereFour Layers Thermosphere Mesosphere Stratosphere Troposphere*

11.1 Our Atmosphere1. Troposphere: where

we live2. Stratosphere:

contains the ozone layer

3. Mesosphere: where the temperature is coldest

4. Thermosphere, where the temperature is highest

Other layers The ionosphere is part

of the thermosphere and is where the Sun’s ultraviolet light creates charged atoms and molecules called ions.

The exosphere begins at about 500 kilometers above Earth’s surface and does not have a specific outer limit.