The Earth's atmosphere acts like a greenhouse's ceiling; it traps heat and lets cold air go into space and into the ground. Atmosphere is a layer of gases that is important in keeping the Earth warm.
The Earth gets warmer and warmer when the Sun's heat rays get absorbed into the atmosphere and transferred into the air and ground. The certain gases that trap the Sun's energy are: water vapor, carbon dioxide, nitrous oxide, and methane. If these gases were not here, then Earth's average temperature would be 60°F colder. But, too much of these gases may result in overheating of the Earth. Many scientist believe that this is one of the main causes of the global warming.
Why do we call this the Greenhouse effect? Greenhouses look like small glass houses. The glass panels trap the Sun's heat inside to keep plants warm enough to survive through the winter without letting the heat escape. One example of the greenhouse effect is a car that has its windows closed and has been in sunlight for a long time. The windows trap the heat.
The greenhouse effect is important to the Earth, or else it would not be warm enough to live on. But, even a slight increase in the warmth could make life hazardous for humans, plants, and animals. It can melt the ice caps, cause huge storm systems and make life on Earth very difficult because of scorching temperatures that can harm health.