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Science 8.____
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Weather & Water Final Exam Study Guide
Investigations 1, 2, 4, 5
Investigations 1 and 2: What is weather? Where’s the air?
1. Define the following terms
 Meteorology– The study of Earth’s atmosphere & weather

Severe Weather – weather that causes damage and destruction

Atmosphere – the layer of gases surrounding the Earth

Forecast – a prediction about future weather
2. Describe the layers of the atmosphere:

Troposphere – the lowest layer of the atmosphere. This is where we live & where all weather occurs.
This layer contains 85% of the atmosphere’s mass

Stratosphere – the second layer of the atmosphere; contains the ozone layer which protects us from too
much UV radiation

Mesosphere – the middle layer of the atmosphere. This layer protects us because it is where meteors
burn up.

Thermosphere – the 4th layer of the atmosphere. The ionosphere is located within this layer which is
where the Northern & Southern lights occur

Exosphere – the outermost layer of our atmosphere; acts as a transition layer to outer space
3. For the weather instruments below, indicate the weather factor that it measures and the units used.

Barometer – measures air pressure in millibars (mb)

Thermometer – measures temperature in Celsius or Fahrenheit

Hygrometer – measures relative humidity as a %

Wind Vane – measures wind direction

Anemometer – measures wind speed in miles per hour or kilometers per hour
4. What is the difference between mass and weight? Mass is the amount of matter in an object, where weight is
a measure of the gravitational pull on an object
5. What are the two most abundant gases found in Earth’s atmosphere and their percentages?
Nitrogen (78%) and Oxygen (21%)
6. What are the two most common variable gases found in Earth’s troposphere?
Carbon dioxide and water vapor
Investigation 4: Heat Transfer
16. Define the following terms:

Heat- molecular motion

Radiation – the transfer of energy without direct contact

Differential Heating – different materials heat up at different rates

Conduction – the transfer of energy by direct contact

Re-radiation – when an object gives off energy it previously received

Kinetic Energy – the energy of moving molecules
17. Explain how the atmosphere is heated. Include a sketch. Be sure to include the following:
a. Radiation
b. Conduction
c. Re-radiation
d. How the ground contributes to the heating.
e. Kinetic Energy
The sun heats the ground by radiation. The ground re-radiates energy to the carbon dioxide and water vapor in
the atmosphere. Also, air in contact with the ground absorbs energy by conduction. As the air gains energy, the
air molecules move more rapidly and this warm air rises.
Investigation 5: Convection
18. Define the following terms:

Convection –the rising and cooling of air due to temperature differences which cause density
differences

Convection Cell – when air rises & sinks due to temperature & density differences, it creates a
continuous movement called a convection cell

Density – how much matter is in a certain volume of material

Mass –the amount of matter in an object

Volume – how much space an object takes up
19. What is the density equation?
D=m/v
20. A student mixed two salt solutions and wanted to know which was denser. She had 30 mL of solution A,
and its mass was 45 g. She also had 40 mL of solution B, and its mass was 50 g. Which solution was denser?
Be sure to show all of your work!
D=m/v
Solution A: d = 45 g / 30 mL = 1.5 g/mL
Solution B: d = 50 g/ 40 mL = 1.25 g/mL
Solution A is denser.
21. What is the relationship between density and temperature?
Warm materials have more energy so their molecules spread out and become less dense.
Cold materials have less energy so their molecules get close together & become more dense.
22. How do convection cells form in the atmosphere? Include the following information:
a. How Earth’s surface is heated.
b. How the air above Earth’s surface is heated.
c. How temperature affects the density of the air
d. If the air rises/sinks
The sun heats the ground by radiation. The ground re-radiates energy to the carbon dioxide and water vapor in
the atmosphere. Also, air in contact with the ground absorbs energy by conduction. As the air gains energy, the
air molecules move more rapidly and this warm air rises because it is less dense. As that air rises, it cools. As
it cools, it becomes more dense and sinks. As this air sinks toward the ground, it re-heats by conduction & reradiation, starting the convection cycle once again.
23. Below, draw a diagram to support your explanation of convection cells in Earth’s atmosphere.