Download ES chapter 11: the atmosphere

ES-11.1: The Air Around You (Key Concept Summaries)
Describe the composition of Earth’s atmosphere and give an example of how events in one
part affect other parts of the atmosphere.
ES-11.1: The Air Around You (Enrichment)
Earth’s atmosphere once contained almost no oxygen, but as the planet changed, so did
the atmosphere. Read the following passage. Then answer the questions that follow on
a separate sheet of paper.
How Earth’s Atmosphere Got Its Oxygen
When Earth’s atmosphere first formed, it contained little, if any, oxygen. How, then, did our oxygenrich atmosphere come about? The answer is life, which first appeared in the form of bacteria about
3.5 billion years ago.
By about 2.5 billion years ago, oxygen-producing organisms, called cyanobacteria, had evolved.
Evolution
is the process by which organisms change to give rise to new organisms over time. The cyanobacteria
took in carbon dioxide and water and produced oxygen as a waste product. Over time, the oxygen they
produced accumulated in the atmosphere. Some of this oxygen was converted to ozone by the sun’s
energy. This was important later for the development of life on land because as ozone increased, it
protected Earth’s surface from too much ultraviolet radiation.
By 700 million years ago, the oxygen concentration had reached about ten percent of the current level,
and organisms made up of many cells had evolved. By 450 million years ago, the ozone level was getting
close to its present value. Soon after that land plants evolved. Land animals followed about 380 million
years ago. Both oxygen and ozone reached their current levels about 300 million years ago. By then
there were many different kinds of complex land plants and animals living on Earth.
1. How did life influence the development of Earth’s atmosphere?
2. What role did ozone play in the evolution of life on Earth?
3. What do you think Earth’s atmosphere would be like today if life had not evolved on Earth?
ES-11.2: Air Pressure (Key Concept Summaries)
Explain what air density and air pressure are, and how altitude affects these properties of
air.
ES-11.2: Air Pressure (Enrichment)
Weather maps have special lines that show different areas of air pressure. Read the
passage and examine the map. Refer to the map to complete the statements below.
Isobars and Air Pressure
Air pressure is an important factor affecting weather. Changes in air pressure help weather forecasters
predict how the weather will change. Falling air pressure usually indicates stormy weather. Rising air
pressure means that the weather is clearing. Air pressure readings from barometers are shown on
weather maps, like the one below, with lines called isobars. Isobars are drawn to connect areas that have
the same air pressure.
1. Each isobar differs from the next isobar by
miillibars.
2. The lowest air pressure reading shown is
millibars.
3. Where this low pressure occurs, the weather is likely to be
.
4. The highest air pressure reading shown is
millibars.
5. This high-pressure area is likely to be experiencing
weather.
6. An area of
air pressure is centered northwest of Chicago.
ES-11.3: Layers of the Atmosphere(Key Concept Summaries)
Describe the characteristics of the four main layers of the atmosphere.
ES-11.3: Layers of the Atmosphere (Enrichment)
Earth’s weather occurs in the troposphere, and air pressure is an important factor in
weather. Use the data on air pressure in the table to make a graph showing how air
pressure changes as you move upward in the troposphere. Then answer the questions
below on a separate sheet of paper.
Air Pressure in the Troposphere
Altitude
(m above sea level)
0 (sea level)
Average Air
Pressure
Altitude
(m above sea level)
Average Air
Pressure
1013.2
5,500
505.4
500
954.6
6,000
472.2
1,000
898.8
6,500
440.8
1,500
845.6
7,000
411.0
2,000
795.0
7,500
383.0
2,500
746.9
8,000
356.5
3,000
701.2
8,500
331.5
3,500
657.8
9,000
308.0
4,000
616.6
9,500
285.8
4,500
577.5
10,000
265.0
5,000
540.5
1. Describe the relationship between altitude and air pressure shown in the graph.
2. Estimate the average air pressure in a hole 500 meters below sea level.
3. If you were flying in a plane at an altitude of 1,500 meters, what would the air pressure outside
the plane be? When you fly that high, why might your ears “pop”?
ES-11.4: Energy in Earth’s Atmosphere (Key Concept Summaries)
Briefly explain how energy from the sun travels to Earth and describe what happens to
this energy as it passes through the atmosphere.
ES-11.4: Energy in Earth’s Atmosphere (Enrichment)
Read the following passage and examine the figure. Then use the figure to answer the
questions below on a separate sheet of paper.
Reflection of Solar Radiation
On average, about half of the sunlight that strikes Earth’s atmosphere reaches the surface of the
planet to be absorbed and converted to heat. This absorbed light is a key factor in determining Earth’s
temperature and weather. Also it is crucial for the normal functioning of Earth’s greenhouse effect.
The other half of the sunlight that strikes the Earth’s atmosphere is either absorbed by the atmosphere
or reflected back into space by clouds or by Earth’s surface itself. The amount of sunlight that is reflected
back into space in a particular place depends mainly on how thick the clouds are and whether Earth’s
surface is dark or light. The figure below shows how much energy is reflected back into space with
different thicknesses of cloud cover and different types of surface on Earth.
1. Which two types of surface on Earth are most important for absorbing solar energy and keeping the
planet warm? Explain your answer.
2. Why do skiers often get sunburned even in the winter, when the sun’s rays are not very strong?
3. What effect would thick cloud cover have on the temperature of Earth’s surface? Explain.
4. Why might a major volcanic eruption lead to cooler temperatures over a large area around a
volcano?
5. Which do you think would be warmer on a winter day when there is no wind, a thick forest or a
grassy field? Explain your answer.
ES-11.5: Heat Transfer(Key Concept Summaries)
Explain how energy from the sun becomes thermal energy on Earth and how that energy
raises the temperature of the troposphere.
ES-11.5: Heat Transfer (Enrichment)
Read the following passage and examine the figure. Then answer the questions below
on a separate sheet of paper.
Heat and Human Health
Extremely hot weather can be dangerous to human health. During a heat wave, the body struggles to
maintain a healthy temperature of about 37°C. Heat stress may set in before the air temperature exceeds
this mark, however, because the body also produces heat when it does work. The figure shows how the
brain and body respond to excessive heat.
The additional stress this response places on the heart and blood vessels can trigger heart and other
medical problems, especially in the elderly. Because of this, death rates often rise when a heat wave
strikes.
1. The brain detects when
the body is too warm
and stimulates other
body parts to respond.
3. Sweating increases
and evaporation of
the sweat helps cool
the body’s surface.
2. Blood vessels expand
and the heart beats
faster to increase
blood flow to the
body’s surface.
4. The body
becomes
dehydrated if
the fluid lost
in sweat is not
replaced.
1. Heat can be lost from the body in the same ways that heat is lost from Earth’s surface. Based on
what you know about heat transfer from Earth’s surface to the atmosphere, describe how the body
can lose heat in each of these ways.
2. The body also loses heat by the evaporation of sweat. How is a tea kettle boiling similar to the
evaporation of sweat from the body?
3. Why are you more likely to become dehydrated in hot weather?
ES-11.6: Winds(Key Concept Summaries)
Describe what causes winds to form and explain how local winds and global winds differ.
ES-11.6: Winds (Enrichment)
In cities, large buildings and other obstacles can change the direction of the wind and make it difficult to
tell from which direction the wind is blowing. To get the true direction of the wind over a city, it is better to
observe how the clouds are moving. You can make a simple device, called a nephoscope, to track cloud
movement. Follow the directions given. Then answer the questions below on a separate sheet of paper.
Using Clouds to Measure the Wind
With a large mirror and a grease pencil or marker that will write on glass, go outside in an open area on
a day with some wind and clouds. Place the mirror face up on the ground. (CAUTION: Handle the mirror
carefully so it does not break.) Use a compass to determine the four directions and mark them on the
four sides of the mirror. Now your nephoscope is ready to use.
To measure cloud direction, watch the mirror for cloud reflections to appear. Put an X in the reflection of
a cloud as it appears on the edge of the mirror. As the reflection of the cloud moves across the mirror,
plot its course by putting more Xs along its path. After the cloud’s reflection has passed across the
mirror, join the Xs with a line and use the line to determine the overall direction of the cloud.
1. What wind direction did your nephoscope indicate? How does that direction compare with the
direction based on on-the-ground indicators, such as wind vanes, flags flying, or smoke drifting? If
the directions are different, what do you think is the reason?
2. Why is a nephoscope a more accurate indicator of wind direction over a city than a wind vane on the
ground?
3. Can you think of any disadvantage in depending on a nephoscope to measure wind direction?