EXPERIMENTAL PROTOCOL
Investigating the greenhouse effect
Introduction
Anthropogenic action has led to an increase in the greenhouse effect and a change in the surface albedo, which alters the Earth’s thermal balance and causes global warming and significant climate change.
The greenhouse effect is a process that occurs when energy from a planet’s sun goes through its atmosphere and warms the planet’s surface, but the atmosphere prevents the heat from returning directly to space, resulting in a warmer planet. Light arriving from our Sun passes through Earth’s atmosphere and warms its surface. The warmed surface then radiates heat, which is absorbed by greenhouse gases such as carbon dioxide. Without the natural greenhouse effect, Earth’s average temperature would be well below freezing. Current human-caused increases in greenhouse gases trap greater amounts of heat, causing the Earth to grow warmer over time
Albedo is the fraction or amount of sunlight reflected by a surface or object. It is often expressed as a percentage and is related to the colour of a surface or object. For example, snow-covered surfaces or deserts reflect a large fraction of sunlight and therefore have a high albedo. In turn, vegetation covered surfaces and oceans reflect a small fraction of sunlight and have low albedo. Changes in the Earth’s surface albedo affect the energy balance of the planet. If there is extensive snow melt, more energy will be absorbed, leading to more surface heating and more snow melt. On a large scale, this has implications for our climate.
Objective
Recreate the greenhouse effect in a container;
Understand the influence of albedo on surface temperature.
Materials used:
Acetate marker
1 Clear glass container (or a transparent plastic bag)
4 small thermometers – for ambient temperature
2 incandescent lamp lamps
1 black and 1 white A4 cardstock
Process:
1. Identify the thermometers with the numbers 1, 2, 3 e 4.
2. Place the thermometers 1 and 2 under the light of a lamp with an incandescent lamp and wait two minutes.
3. Write down the value of the temperature registered on thermometers 1 and 2 and the initial time.
4. Place the container on top of thermometer 2(if the thermometer is too large, it can be placed vertically).
5. Every two minutes, for ten minutes, record the temperature value on thermometers 1 and 2.
6. Build a graphic with the data obtained.
7. Place the thermometers 3 and 4 under the light of a lamp with an incandescent lamp and wait two minutes.
8. Write down the value of the temperature registered on thermometers 3 and 4 and the initial time.
9. Place thermometer 3 inside the white cardboard previously folded in half and thermometer 4 inside the black cardboard, also folded in half.
10. After 5 and 10 minutes register the value of the temperature on the thermometers 3 and 4.
Results:
Thermometer 1 e 2
Initial temperature:
Thermometer 1-____ Thermometer 2-____
Temperature(ºC)
Discussion of results
1. Indicate the function of thermometer 1.
2. Explain what the glass container represents.
3. Which one of the thermometers 1 or 2 registered the highest increase of temperature. Justify your answer.
4. The increase in the amount of greenhouse gases in the Earth’s atmosphere has the same effect as that observed in the glass container. What are its consequences?
5. Which thermometer 3 or 4 registered the highest increase of temperature. Justify your answer.
6. What phenomenon was intended to represent with thermometers 3 and 4?
7. What is the importance of vegetation cover in maintaining the average temperatures in cities?
Conclusions:
(Aswers to question 4 and 7).
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