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              2—Why is Pollution an Environmental Issue? 40 Environmental Pathways
Earth Atmosphere Model Instruction Sheet
Materials Needed
• one sheet of white paper 1 meter by 1 meter in size (bulletin board paper works well)
• a metric ruler
• pencil and colored pencils
• a round object such as a jar lid or milk cap
Activity
Check off each instruction after you have completed it. Remember, when drawing a new layer of the
atmosphere, you should measure from the Earth’s surface, not the layer before it.
❏ Obtain a 1 meter by 1 meter piece of paper.
❏ Use a pencil to trace a round object in the middle of the paper. This is Earth. Color Earth blue and
green to represent oceans and continents.
❏ The first layer of Earth's atmosphere, the troposphere, extends 10-15 km above earth. Using a scale
of 1 mm for 1 km, place a series of dots around Earth, 20 mm from the planet's surface. Connect the
dots to form a circle around Earth. Label the inside of this circle 'troposphere.' Draw pictures to indicate
that this is the area in which airplanes fly and weather happens.
❏ The second atmospheric layer, the stratosphere, extends 50 km above Earth's surface. Measure
and draw a circle 50 mm from Earth's surface. Label this layer 'stratosphere.' The jet stream occurs
between the troposphere and the stratosphere, so draw arrows to represent this fast moving current of
air on the borderline between the two layers.
❏ The third layer of the atmosphere, the mesosphere, extends 90 km from Earth's surface. Measure,
draw, and label this layer. This is the coldest layer, so draw a thermometer to represent the very cold
weather.
❏ The ozone is between the stratosphere and mesosphere. Ozone is made of three atoms of oxygen.
Along the border of the stratosphere and mesosphere, draw molecules of ozone - three connected
dots - leaving a tiny area empty to represent the 'hole' in the ozone layer.
❏ The fourth layer of the atmosphere, the thermosphere, extends 480 km above Earth's surface.
Measure, mark, and label this layer. A thin region in the thermosphere, called the ionosphere, contains
charged atoms. Label the ionosphere and draw + and - signs to represent those atoms. (Remember, this
is not a layer, just a region in the thermosphere.) When meteoroids enter Earth's atmosphere, they enter
the thermosphere. Because of the heat caused by friction with molecules in the atmosphere, most mete-oroids
burn up. A meteoroid falling through Earth's atmosphere is called a meteor. Draw and label a
meteor.