1. Heating Earth’s Surfaces
6th Grade Science

2. The state of the atmosphere at any one time.
Weather
The state of the atmosphere at any one time.

3. Factors involved in weather
Moving Air
Water
Land
Heat from the sun

4. Heating Earth’s Surfaces
Your Purpose
To perform an experiment to investigate how the sun’s energy heats different Earth Surfaces (water & land)
Title your lab:
Heating Earth’s Surfaces

5. Do you agree or disagree?
The sun’s energy can heat the Earth’s surfaces, even though it is millions of KM away.
The sun’s energy heats both land and water the same temperature.
After being heated, land cools faster than water?
Differences in land and water affect weather and climate?

6. Why are we learning this?
The heating and cooling of land and water is one factor of weather.

7. Each group will have the same materials:
50 mL of water
50 mL of sand (land)
2 plastic-backed thermometers
1 graduated measuring cup
2 white plastic trays to hold the sand and water
2 clear plastic films to protect the thermometers from the light.
All groups will use the same heat source – the lamps in the front of the room.
A timer on the front screen.

8. Before beginning: Take a look at the materials.
Think about how you create an experiment that tests whether land and water heat and cool the same or will they be different?
How could you find an answer to this question using only these materials?
You have 5 minutes – brainstorm with your group about how you could test this procedure using the materials in front of you, a heat source, and one class timer on the front board.

9. Procedure
Let’s discuss our ideas. Please listen to hear what each group has to say.
Because we only have one stopwatch to use in the class, we will each have to follow the same procedure.
Let’s review the procedure that we all will follow.

10. Here is the procedure we will follow.
How did it compare with the one you created?

11. Create a hypothesis
Think about the statements you either agreed or disagreed with.
Do you think land and water heat and cool the same or will they be different?
Why or why not?
Write your hypothesis on your page. Remembers to include what you think will happened AND why.
Example: I predict that both sand and water will heat and cool the same because they will both be using the same heat source.

12. Collecting your data What will your data prove?
Your data should be used to reach a conclusion. Based on the results, you should be able to conclude…
Example: …if there is any difference in the temperatures of the land and water during heating and cooling, and if they are affected differently by the sun’s energy.

13. Create your data collection tool:
Time Minutes
Temperature of Sand C°
Temperature of Water C°
Heat source? N 2 Y 4 6 8 10 12 14 16 18 20

14. Graphing Your Results Organize your data so it makes sense!
What type of graph would you make?
Are we showing changes over time?
YES! Create a line graph!

15. Conclusion
What can you conclude about how land & water heat up and cool down?
Was your hypothesis supported? Why or why not?
Support your answer with evidence from this activity – use numbers!
Write your conclusion on your page.
Clean and return your materials.
Turn in your page for credit for today’s lab.

16. Unequal Heating of the Atmosphere
Effects
Warm air expands, becomes less dense, and rises.
Cause
Cold, more dense air sinks.
Unequal heating of the atmosphere
Dense cold air has a higher pressure than less dense warm air. Wind blows from areas of higher pressure to areas of lower pressure.

17. Warm and Cold Fronts
An air mass is a large volume of air in which the temperature & humidity are nearly the same.
Air masses gradually take on the characteristics of the land below it – if the earth is cold, the air becomes cold.
Air masses can travel away from where they form. They move with the global patterns of the wind.
A front is an area where 2 air masses make contact; the boundary between 2 air masses.
When a cold and a warm air mass meet, there is a weather change.
The boundary between the warm and cold air masses always slopes upwards over the cold air. This is due to the fact that cold air is much denser than warm air.

18. How a Front Forms
The boundary where unlike air masses meet is called a front.

19. Warm Fronts

20. Warm Fronts
A. Warm front: created when a warm air mass And a cold air mass meet.
Because it is less dense, warm air has a harder time displacing denser, cold air. The boundary separating these air masses acquires a very gradual, gentle slope.
As the warm air ascends, it expands and cools to produce clouds and frequently precipitation.
Because of their slow rate of advance and very low slope, warm fronts usually produce light to moderate precipitation over a large area for an extended period.
Warm fronts are characterized by several days of steady precipitation.

21. Cold Fronts

22. Cold Fronts
Cold front: created when a cold air mass replaces a warm air mass.
Cumulonimbus clouds form.
The fast moving, heavy, cold air mass pushes under the warm air and lifts it quickly creating a steep frontal surface. (looks like the front of an airplane.)
Cold fronts are characterized by sudden, short, violent thunderstorms.
Cold fronts advance faster than warm fronts.
Friction between the advancing cold front and the warm front leads to colds front being twice as steep as warm fronts.
The increased speed and steepness of slope are responsible for the more violent nature of cold front weather.
The intensity of precipitation is much greater at a cold front, although it is usually short in duration.

23. High and Low Pressure Systems
Highs and lows are due to the unequal heating of air masses.
High-pressure areas:
Winds blow outward; clockwise; air pressure is highest at center;
Usually brings bright blue clear skies; calm air, and fair cool weather.
Low-pressure areas:
Winds blow inward toward center; counter clockwise; air pressure is lowest at center.
Usually brings cloudy skies; precipitation and warm weather

24. High and Low Pressure Areas
Air rises in low pressure areas and forms water droplets
Usually results in rain and storms
High pressure causes air to sink
Usually results in several days of clear sunny skies

25. How wind forms
Wind moves from an area of high pressure to an area of low pressure
Sunlight strongly heats an area of the ground. The ground heats the air. The warm air rises, and an area of low pressure forms.
Sunlight heats an area of ground less strongly. The cooler, dense air sinks slowly and an area of low pressure forms.
Air moves as wind across the surface, it moves from higher to lower pressure.

26. Global Wind Belts The distance wind travels varies.
Global winds travel thousands of kilometers in steady patterns.
Formed by two main factors:
unequal heating of the earth by sunlight
the earth's spin.
The unequal heating makes the tropical regions warmer than the polar regions. As a result, there is generally higher pressure at the poles and lower at the equator. Wind flows from high to low pressure.
So the atmosphere tries to send the cold air toward the equator at the surface and send warm air northward toward the pole at higher levels.
The spin of the earth prevents this from being a direct route, and the flow in the atmosphere breaks into three zones between the equator and each pole.

27. Angle of the Sun’s Rays
Energy from the sun strikes Earth most directly near the equator. Near the poles, the same amount of energy is spread out over a larger area.

28. Some sunlight is absorbed or reflected by the atmosphere
Some sunlight is absorbed or reflected by the atmosphere. The rest passes through to the surface.

29. Greenhouse Effect
When Earth’s surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation. Much of this energy is held by the atmosphere, warming it.