Download unit study guide – atmosphere

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UNIT STUDY GUIDE – ATMOSPHERE
Word
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
Ozone
Nitrogen
Humidity
Climate
Meteorology
Oxygen
Weather
Density
Ultraviolet (UV)
Rays
Greenhouse Gas
Greenhouse
Effect
Carbon Dioxide
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Definition
The troposphere starts at the Earth's surface and is the most dense. Almost
all weather is in this region.
The stratosphere starts just above the troposphere. The ozone layer, which
absorbs and scatters the solar ultraviolet radiation, is in this layer.
The mesosphere starts just above the stratosphere and meteors burn up in
this layer.
The thermosphere starts just above the mesosphere. Auroras and satellites
occur in this layer.
This is the upper limit of our atmosphere. It extends from the top of the
thermosphere and is where space and our atmosphere meet.
Ozone is a gas made up of three oxygen atoms (O3). It occurs naturally in
small (trace) amounts in the upper atmosphere (the stratosphere). Ozone
protects life on Earth from the Sun’s ultraviolet (UV) radiation.
A colorless, odorless, gaseous element that constitutes about four-fifths of
the volume of the atmosphere and is present in animal and vegetable
tissues, especially in proteins.
A quantity representing the amount of water vapor in the atmosphere.
Describes weather conditions over a long period of time and over an
entire region.
Branch of science concerned with the processes and phenomena of the
atmosphere, especially as a means of forecasting the weather.
Oxygen is a colorless and odorless molecule that is a gas at room
temperature and is needed for organisms to survive. It makes up over
twenty percent of the Earth’s atmosphere.
The temporary state of the atmosphere at a place and time with regard
to heat, dryness, sunshine, wind, rain, etc.
The density of a substance is the relationship between the mass of the
substance and how much space it takes up (volume). The mass of atoms,
their size, and how they are arranged determine the density of a
substance.
Part of the light spectrum that comes from the sun and can be harmful to
humans. Most UV rays are absorbed in the ozone layer.
Many chemical compounds found in the Earth’s atmosphere act as
“greenhouse gases.” These gases allow sunlight to enter the atmosphere
freely. When sunlight strikes the Earth’s surface, some of it is reflected back
towards space as infrared radiation (heat). Greenhouse gases absorb this
infrared radiation and trap the heat in the atmosphere.
Heat from the Earth is radiated outward and absorbed by the
greenhouse gases in the atmosphere. This process prevents heat from
disappearing into space and keeps Earth warm enough to sustain life. In
recent years, this effect has also caused Earth’s average temperature to
raise.
When a carbon atom and two oxygen atoms bond together, they form a
colorless, odorless gas called carbon dioxide, which is a heat-trapping
greenhouse gas. Whenever we burn fossil fuels such as coal, oil, and
natural gas, we are producing carbon dioxide.
Answer the following questions below in complete sentences.
1. Describe the difference between weather and climate.
Weather is the daily conditions of the atmosphere in terms of temperature, atmospheric
pressure, wind, and moisture. Climate is the weather conditions prevailing in an area in
general or over a long period.
2. How will Earth’s climate be affected if the glaciers continue to melt at the current rate?
When temperatures rise and ice melts, more water flows to the seas from glaciers and ice
caps, and ocean water warms and expands in volume. This combination of effects has played
the major role in raising average global sea level between four and eight inches (10 and 20
centimeters) in the past hundred years.
3. What is the composition of the air we breathe? Give the percentages of the each type of
gas.
Air is a gaseous substance that is composed primarily of nitrogen, oxygen and argon. The air
in the atmosphere that surrounds the Earth is approximately 78 percent nitrogen, 21
percent oxygen and 1 percent argon, with the remainder made up of various
other gases including neon, helium and hydrogen.
4. Describe the ozone layer. Why is it important for us to understand the changes to the
ozone?
Ozone is a gas made up of molecules that are formed by three oxygen atoms. Its molecule formula is
O3. Ozone is formed when the sunlight hits oxygen molecules (O2) and breaks them up into
individual atoms. These individual atoms then join up with O2 molecules and make O3, or ozone.
Ozone molecules in the atmosphere provide us with important protection from the rays of the sun.
Specifically, these molecules are good at absorbing certain ultraviolet rays that can cause sunburn
and skin cancer.
5. List the layers of the atmosphere in order from Earth to space. Describe two things about each.
1. Troposphere- where all weather occurs, is the layer with the most density.
2. Stratosphere- where the Ozone layer exists, the temperature increases because of the presence of Ozone.
3. Mesosphere- temperature decreases as altitude decreases, it is about 50 miles from Earth. Air is very thin,
temperatures can be -148*.
4. Thermosphere- The temperature in the thermosphere increases and it can be higher than 2732º F (1,500º
C). The air in the thermosphere would feel cold because the molecules of nitrogen and oxygen which absorb
the Sun's energy are so far apart that the heat concentration is ineffective.
5. Exosphere- In exosphere, molecules of hydrogen, atomic oxygen, helium, carbon dioxide, etc., are found.
Here they are sparsely dispersed. Earth's gravity acts even on these molecules and the ions in the
atmosphere and pulls them to it.
6. Describe how density changes as you go up through the atmosphere.
Density is a measure of how closely molecules are packed together. The closer together they are, the greater
the density. Since air is a gas, the molecules can pack tightly or spread out.
Altitude is height above sea level. The density of air decreases with height. There are two reasons: at higher
altitudes, there is less air pushing down from above, and gravity is weaker farther from Earth's center. So at
higher altitudes, air molecules can spread out more, and air density decreases.
7. Describe how temperature changes as you go up through the atmosphere.
Temperatures rise and fall, or decrease and increase, as you go up in altitude depending on the
composition of each layer of the atmosphere. For example, the temperature of the Troposphere
decreases with height because the air is less dense. As you go into the Stratosphere, the
temperature increases due to the presence of Ozone, which absorbs ultraviolet rays.