Is it true that the wave length of energy radiated from the earth back into the atmosphere is longer than the incoming solar radiation?

Yes, it is true. The energy radiated from the Earth back into the atmosphere is primarily in the form of infrared radiation, which has a longer wavelength compared to the incoming solar radiation, which is predominantly in the visible spectrum and has shorter wavelengths. This difference in wavelength is due to the Earth's surface temperature being much lower than that of the Sun. As a result, while solar radiation peaks in the visible range, Earth's emitted radiation peaks in the infrared range.