Greenhouse gases warm the atmosphere by trapping heat. Some of the heat radiation out from the ground is trapped by greenhouse gases in the troposphere. Like a blanket on a sleeping person, greenhouse gases act as insulation for the planet. The warming of the atmosphere because of insulation by greenhouse gases is called the greenhouse effect. All are a normal part of the atmosphere except CFCs. The table below shows how each greenhouse gas naturally enters the atmosphere.
Different greenhouse gases have different abilities to trap heat. For example, one methane molecule traps 23 times as much heat as one CO 2 molecule. Still, CO 2 is a very important greenhouse gas because it is much more abundant in the atmosphere. Human activity has significantly raised the levels of many of greenhouse gases in the atmosphere. Carbon dioxide has increased more than 35 percent. CFCs have only recently existed. What do you think happens as atmospheric greenhouse gas levels increase?
More greenhouse gases trap more heat and warm the atmosphere. The increase or decrease of greenhouse gases in the atmosphere affect climate and weather the world over. Not surprisingly, many pots and pans have insulated handles.
Air a mixture of gases and water are poor conductors of thermal energy. They are called insulators. Conduction, radiation and convection all play a role in moving heat between Earth's surface and the atmosphere.
Since air is a poor conductor, most energy transfer by conduction occurs right near Earth's surface. Conduction directly affects air temperature only a few centimeters into the atmosphere. During the day, sunlight heats the ground, which in turn heats the air directly above it via conduction. At night, the ground cools and the heat flows from the warmer air directly above to the cooler ground via conduction.
However, they also radiate their energy faster than lighter colored objects. Learning Lesson: Melts in your bag, not in your hand. Conduction is the transfer of heat energy from one substance to another or within a substance. Have you ever left a metal spoon in a pot of soup being heated on a stove? After a short time, the handle of the spoon will become hot. This is due to transfer of heat energy from molecule to molecule or from atom to atom. Also, when objects are welded together, the metal becomes hot the orange-red glow by the transfer of heat from an arc.
This is called conduction and is a very effective method of heat transfer in metals. However, air conducts heat poorly. Convection is the transfer of heat energy in a fluid. This type of heating is most commonly seen in the kitchen with a boiling liquid. Air in the atmosphere acts as a fluid. The sun's radiation strikes the ground, thus warming the rocks. As the rock's temperature rises due to conduction, heat energy is released into the atmosphere, forming a bubble of air which is warmer than the surrounding air.
This bubble of air rises into the atmosphere. As it rises, the bubble cools with the heat contained in the bubble moving into the atmosphere. As the hot air mass rises, the air is replaced by the surrounding cooler, more dense air, what we feel as wind.
These movements of air masses can be small in a certain region, such as local cumulus clouds, or large cycles in the troposphere, covering large sections of the earth.
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