Answer:
This is called the Greenhouse Effect.
Step-by-step explanation:
The greenhouse effect is the mechanism by which some molecules in an atmosphere contribute to the planet's ability to retain heat. There are two concepts to grasp: two factors: 1) how heat energy escapes from warm objects; and 2) how some gases prevent the heat energy from escaping.
1. How heat energy escapes from warm objects
Anything that is warmer than absolute zero (-273.15 °C) emits electromagnetic radiation, or "glows." That is to say, any warm object radiates electromagnetic waves that carry some of the heat energy along with them as they travel away from the object.
Electromagnetic radiation: What is it? Waves are what move and convey energy through space. The amount of energy that a wave can carry increases with its frequency (waves per second). Low frequency electromagnetic radiation is referred to as "radio." Visible light is a much higher frequency type of electromagnetic radiation. X-rays operate at an even higher frequency.
The range of frequencies that warm objects produce depends on the object's temperature. We can see objects that are really hot glow because they emit a lot of visible light. Although cooler objects don't produce visible light, they nevertheless glow from low frequency electromagnetic radiation that is unseen. The average surface temperature of the Earth is 15 °C, and objects at this temperature emit "infra-red" electromagnetic waves, which have a lower frequency than red light and cannot be seen by human eyes. Since the sun's surface is about 6,000 degrees Celsius hotter than Earth's, it emits visible light. The fact that anything with a temperature above absolute zero glows is similar in many ways.
The Earth is 'glowing' with invisible infrared simply because it is warm. The infra red takes heat energy away from the Earth. It disappears into space.
2. How some gases stop the heat energy escaping
A molecule can vibrate. The tensions between the atoms that make up molecules resemble tiny springs and minuscule balls, respectively. The balls can be rhythmically brought closer together and farther apart by the springs as they compress and stretch. One approach to temporarily store energy is to cause a molecule to vibrate.
When electromagnetic waves strike a molecule, if they are of the proper frequency, the wave's energy can be converted into the vibrational energy of the molecule. In other words, the electromagnetic wave's energy is stored in the molecule. However, it doesn't retain the energy for very long before ceasing to vibrate and converting it back into an electromagnetic wave.
Which frequencies cause the molecule to vibrate depends on its characteristics. The frequencies at which carbon dioxide, methane, and other greenhouse gases vibrate are the same as those of infrared light. Because they don't vibrate at the same frequencies as nitrogen and oxygen molecules, infrared radiation passes right by them. On the other hand, there is a good chance that a carbon dioxide molecule will absorb an infrared wave's energy and momentarily store it as a vibration if it does so.
It's important to note that a vibrating molecule can eventually emit a wave that travels in any direction, including up, down, left, right, forward, and backward. Where the initial wave was going is irrelevant.
3. Putting it all together
- Electromagnetic radiation, or heat, is constantly emitted from the Earth's surface.
- Carbon dioxide, methane, and other molecules with the proper vibrational frequencies absorb infrared waves that are traveling out into space, and their energy is momentarily stored as a vibration.
- The infrared wave that results from the vibration's transformation back into a vibration can travel in any direction, including back towards Earth. Its energy will be reabsorbed by the Earth if it comes in contact with the surface.
- Without "greenhouse gases," all of the heat energy contained in the infrared would be carried away into space. Because of the obstruction caused by greenhouse gas molecules, some infrared radiation is reemitted back toward the Earth, replenishing some of the heat energy lost.
- More heat energy will be conserved if we add more greenhouse gas molecules to the atmosphere. The Earth's surface will be hotter the more heat energy there is.
Thanks.