Chapter 30, Problem 9RQ

How does radiation emitted from Earth differ from that emitted by the Sun?

To determine

The difference between radiation emitted by Earth and Sun.

Answer to Problem 9RQ

The difference between radiation emitted by Earth and Sun is that the Earth emits radiation with infrared long-wavelength, whereas the Sun emits radiation with short-wavelength.

Explanation of Solution

The radiation emitted by the Sun is mostly visible short-wavelength part of the spectrum. This energy is consumed by the Earth and re-emit back to space, which is known as terrestrial radiation. This terrestrial radiation is the infrared long-wavelength part of the spectrum.

Maximum all the long infrared waves are emitted back to space, but some of them get trapped in the atmosphere by the gases. This trapped gas causes the temperature of Earth to increases. The radiation emitted by the Earth is between $5-25\text{μm}$, where, in case of radiation by the Sun, the wavelength is less than $2\text{μm}$.

Conclusion:

Therefore, the difference between radiation emitted by Earth and Sun is that the Earth emits radiation with infrared long-wavelength, whereas the Sun emits radiation with short-wavelength.