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STUDY GUIDE
Chapter 13 The Atmosphere
BIG CONCEPT= Events in one part of the atmosphere affect other parts of the atmosphere. Energy
from the sun drives the motions in the atmosphere. The unequal heating of the Earth’s surface
causes convection currents = wind. The air pressure in different locations will change. The level of
air pressure will help determine the type of weather the area will experience.
The atmosphere is held to Earth by the force of gravity.
Be able to identify the various gases that make up the earth’s atmosphere and the percentages of
each.
Nitrogen 78%, Oxygen 21%, trace gases (carbon dioxide, methane, etc) 1%
There is also water vapor and particles of dust, smoke, etc in the air.
Be able to identify the instruments used to measure air pressure, temperature and wind.
air pressure = barometer (mercury or aneroid = used in most homes)
temperature = thermometer
wind direction = wind direction
wind speed = anemometer
Unequal heating of the Earth’s atmosphere causes differences in air pressure around the earth.
Be able to identify the relationship between altitude, air pressure and temperature.
Air pressure decreases as altitude increases or air pressure increases as altitude decreases.
This is caused by gravity.
Temperature decreases as altitude increases in the troposphere.
Temperature increase as altitude increases in the stratosphere.
Air pressure moves from areas of high concentration to areas of low concentration. This
causes wind. With regards to weather: high pressure = good/clear, sunny skies and low pressure =
bad/stormy rain/snow. When reading a weather map, the isobars with larger numbers are high
pressure while the isobars with lower number are low pressure.
Know the order of the earth’s atmospheric layers from the earth’s surface.
Know the general characteristics of each layer and objects/phenomena that may occur in each
layer.
troposphere: closest to Earth’s surface; most dense = air pressure is the greatest in this layer;
most of atmosphere’s mass; all weather; most small and commercial airplanes; temperature
decreases as altitude increases; air pressure decreases as altitude increases
stratosphere: temperature increase as altitude increases; ozone layer (absorbs ultraviolet
rays protecting living organisms on Earth’s surface); military planes; weather balloons will pop in this
layer; Felix Baumgartner record breaking free fall from this layer
mesosphere: coldest layer; meteoroids (“shooting stars”) burn up in this layer
thermosphere: outermost layer; has no definite out limit
ionosphere = lower part of thermosphere; has electronically charged particles creating the
auroras/northern lights; AM radio waves can bounce off the ions
exosphere = upper part of thermosphere; satellites, space shuttle and international space
station orbit earth in this layer; temperatures reach 1800°C but can’t feel the heat because
particles are so far apart = least dense
Understand the 3 parts and differences of the electromagnetic spectrum: infrared radiation, visible
light and ultraviolet light.
Infrared radiation has wavelengths that are longer than visible light and can be felt as heat.
Visible light includes all of the colors that we see. Each color is the result of a different
wavelength. Read has the longest and violet has the shortest
Ultraviolet radiation has wavelengths that are shorter than visible light and can cause
sunburn and skin damage. The ozone layer helps to absorb many UV rays.
Earth’s surface radiates some energy back into the atmosphere as infrared radiation.
The process by which gases in the atmosphere absorb thermal energy & radiate it back to Earth=
greenhouse effect. Without the greenhouse effect Earth would get really cold because all
radiated heat would escape into space.
Global warming is caused by an increase in greenhouse gases.
When heated, most matter expands.
Most solar energy that reaches Earth’s atmosphere is absorbed by Earth’s surface.
Understand the difference between temperature, thermal energy and heat.
Temperature is a measure of the average kinetic energy of the particles in an object. As an
object heats up, its particles move faster. As a result, both the average kinetic energy of the
particles and the temperature increases.
The United States uses the Fahrenheit scale to measure temperature.
Most countries use the Celsius scale. 0° = freezing point of water 100° = boiling point of
water
Many scientists use the Kelvin scale. A temperature change of 1 K(Kelvin) is the same
temperature change as 1°C… however 0 K or absolute zero (the lowest temperature possible
when all movement of particles stop) is equal to -273°C.
Thermal energy is the total energy of all of the particles in an object. It depends on the
temperature of an object, the number of particles in it and how those particles are arranged. The
more particles an object has at a given temperature, the more thermal energy it has. Objects
contain thermal energy. They do not contain heat.
Heat is the transfer of thermal energy from a warmer object (A) to a cooler object (B) = heat
transfer goes from “hot to cold”. The warmer object will cool down and the cooler object will
warm up until they are the same temperature.
When given two objects of different masses and temperatures, be able to tell which has more
thermal heat.
If 2 objects have the same temperature but different masses, the one with larger
mass has more thermal energy. (remember the hot tea example)
If two objects have different temperatures, consider the mass of each object to identify
which has more thermal energy. (remember the match and ice sculpture example)
The atmosphere is heated by conduction, convection and radiation. Know the difference between
the 3 types of heat transfer and be able to identify examples of each.
conduction – the transfer of energy between two substances that are in direct contact;
works best with solids (popcorn – stove)
convection – the transfer of energy by the movement of a fluid; works best in fluids (liquids
and gases) (popcorn – air popper)
radiation – transfer of energy by electromagnetic waves; most heat you feel from the sun
travels to you as infrared radiation, but you feel it as heat (popcorn = microwave)
Heat is transferred mostly by convection within the troposphere.
Air moves in large circular patterns because of convection currents. Convection currents are the
upward movement of warm, less dense air rising and cool, more dense air sinking. (In the Colorful
Convections Lab: when the warm water was on top of the cold water they did not mix. When the
cold water was on top of the warm water, the cold sank and the warm rose, mixing the two.)
When heated, most matter expands.
As the amount of thermal energy increases, particles move faster and farther apart = a solid can
change to a liquid; a liquid can change to a gas
As the amount of thermal energy decreases particles move slower and closer together = a gas
can change to a liquid; a liquid can change to a solid
When chemical reactions give off heat = exothermic reaction (elephant toothpaste)
When chemical reaction absorbs heat = endothermic reaction
Differences in air pressure causes wind.
Because of the Coriolis effect, global winds in the Northern Hemisphere gradually turn toward the
right. A wind blowing toward the south gradually turns toward the southwest. (The opposite
happens in the southern hemisphere.)
The unequal heating of the Earth’s surface create global winds. These occur over large areas.
Be able to read a diagram of the global wind belts and identify how ships with sails can get from
one point to another using these winds. We live in the prevailing westerlies global wind belt.
Differences in air pressure around Earth are caused by warm air rising and cool air sinking.
The jet stream is an example of an atmospheric current. A jet stream is a narrow band of very
strong, predominantly westerly air currents encircling the globe several miles above the earth.
Airplanes traveling west to east can sometimes take advantage of the jet stream – making the trip
much shorter than those traveling east to west into the wind.
The unequal heating of the Earth’s surface within a small area causes local winds. These only form
when large scale/global winds are weak.
Be able to identify that land breezes and sea breezes are local winds. Be able to describe how
and when they occur.
A land breeze occurs when cool air from the land rushes out to replace warm air over water.
A sea breeze occurs when cool air from the water rushes in to replace warm air over land.
Sea Breeze
Land Breeze
Lab Activities:
Be able to describe what happened to the marshmallow in the syringes when we increased the
amount of air pressure (pushed it in) and decreased the amount of air pressure (pulled it out).
Be able to describe why warm water in the syringe boiled when we lowered the air pressure.
Be able to describe why/how the can was crushed and/or how/why the egg got into the bottle
during our class activities.
Be able to explain the Colorful Convection Lab with warm and cold water.
Be able to identify and describe what type of heat transfer was used to pop popcorn using the
stove/concession popper, air popper and microwave.
Be able to explain what type of reaction (endothermic or exothermic) and why the elephant
toothpaste activity demonstrated.
Be able to read a diagram of the global wind belts and identify how ships with sails can get from
one point to another using these winds.