医学环境保护演讲ppt培训课件

Greenhouse effect
How Do Humans Contribute to the Greenhouse Effect?
While the greenhouse effect is an essential environmental prerequisite for life on Earth, there really can be too much of a good thing.
Although greenhouse gases make up only about 1 percent of the Earth's atmosphere, they regulate our climate by trapping heat and holding it in a kind of warm-air blanket that surrounds the planet.
Greenhouse effect
What is the greenhouse effect ?
On a sunny winter day, you park your car in the sun, lock it, and go cruise the local shopping mall for a couple of hours. When you come back later and get into your car, what do you notice? Is the interior of the car hot or cold? How does the temperature inside of your car compare to the temperature outside?
Greenhouse effect
The greenhouse effect is a naturally occurring process that aids in heating the Earth's surface and atmosphere. It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapor, and methane, are able to change the energy balance of the planet by absorbing longwave radiation emitted from the Earth's surface. Without the greenhouse effect life on this planet would probably not exist as the average temperature of the Earth would be a chilly -18° Celsius, rather than the present 15° Celsius
If you have ever been inside of a greenhouse, especially when the sun is out, what have you observed? It is definitely warm, and usually the air is moist. A greenhouse is commonly warmer than the outside air because a greenhouse has the ability to trap heat inside of it. This phenomenon is called the greenhouse effect.
环境保护 演讲
Our topic
What do you know about greenhouse effect? Global warming? Rising sea levels? The impact on the earth?
Outline
• Greenhouse effect • Global warming • Rising sea levels
The heat caused by infrared radiation is absorbed by "greenhouse gases" such as water vapor, carbon dioxide, ozone and methane, which slows its escape from the atmosphere.
Greenhouse effect
Life on the earth depends on energy from the sun. About 30 percent of the sunlight that beams toward Earth is deflected by the outer atmosphere and scattered back into space. The rest reaches the planet's surface and is reflected upward again as a type of slowmoving energy called infrared radiation.
The problems begin when human activities distort and accelerate the natural process by creating more greenhouse gases in the atmosphere
than are necessary to warm the planet to an ideal erature.
Greenhouse effect