Unlike conduction and convection, radiation does not need matter like air, water or metal to transfer heat. In radiation, heat moves through empty space. It travels along electromagnetic waves, which are mostly invisible to the naked eye. All objects constantly emit and absorb radiant energy, even humans.
One example of radiation is the heat energy we get from the sun. This heat travels through the vacuum of space to reach Earth. Earth absorbs some of the sun’s radiant heat and bounces some back into the atmosphere. Gases in the atmosphere absorb some of that radiation and hold it close to Earth’s surface. This keeps the planet warm enough to live on. The gases in the atmosphere that hold heat are called greenhouse gases, and the cycle by which they heat the Earth is called the greenhouse effect.
Based on the passage, which of the following best describes the greenhouse effect?
A
The process by which radiant heat from the atmosphere heats up the Earth’s surface, making it warm enough for humans.
B
The method by which electromagnetic waves carry heat through air or water, leading to balanced temperatures.
C
A type of gas that lets radiant heat escape through holes in the atmosphere, making the Earth cool.
D
A system that allows the sun to absorb enough radiant energy from the Earth to stay hot.
C
A type of gas that lets radiant heat escape through holes in the atmosphere, making the Earth cool.