1. Energy in Ecosystems

2. As mentioned previously, the source of energy for all ecosystems is the sun.
The sun heats the planet, provides energy to evaporate water in the water cycle and allows green plants to make food for them to grow and become food for all other organisms.

3. 1/1,000,000,000
Only one billionth of the sun’s energy reaches Earth after a journey of 150 million kilometres.
Harmful cosmic rays, gamma rays, x-rays and ultraviolet radiation are either reflected or absorbed by chemicals in the atmosphere.

4. Of the energy that penetrates the atmosphere, about 30% is reflected by clouds or the surface of the planet.
The estimated remaining 70% warms the planet and aids in the water cycle. Only 0.023% is actually used by green plants for photosynthesis.
Photosynthesis is the process by which green plants use sunlight energy to produce carbohydrates (sugar).

6. While some of the sun’s energy is absorbed by the earth some of that energy is reflected back only to be trapped by gases in our atmosphere. This is how the planet retains heat during the nighttime.

7. The Albedo Effect
When the sun’s energy hits an object, some of the energy is absorbed, and some is reflected.
Some material reflects sunlight better than others. (Ex) dark shirts vs. white shirts)
Albedo is a measurement of the percentage of light that an object reflects.

9. The higher the albedo, the greater the object’s ability to reflect sunlight.
The reason that you have a hard time seeing on a sunny day in the winter is due to the Albedo Effect.

10. Snow contributes to low temperatures in the winter by reflecting energy from the sun back into space. It also delays warming in the spring.
Other light coloured areas on the planet have similar effects. (Ex. Sand, pale rocks and deforested areas)

11. Questions to Answer 1. Why is sunlight so important to the biosphere?
Biosphere – sum of all ecosystems
2. Using the information provided in this class determine why would periods of low temperatures follow volcanic eruptions?
3. Explain why burrowing animals are most often found in grassland/prairie areas compared to dense forest areas?
4. Draw a diagram that shows the energy flow from the sun to the Earth and how energy is reflected.