Coherence is mostly irrelevant to absorption.
Secondly, sunlight energy attenuation by the atmosphere is FAR greater than that. What you are talking about is the absorption by the troposphere, and that's 50% of the incident sunlight at that point, not the total. Enormous amounts of energy are absorbed in the thermosphere, long before the light reaches the troposphere. You're also confusing radiative energy with convection. Overall, only 5% of the radiative energy of the sun reaches the Earth's surface, not 50%. 50% of the TOTAL energy reaches the Earth, but all of that energy is not radiative, which is what we're talking about here. Furthermore, the process of diffraction of coherent light versus non-coherent light is a totally different process.
What you are looking for is a plot of atmospheric transmission as a function of wavelength. Any large college library should have it.
Good night.