On the one hand, tiny dust particles, smoke particles or salt particles (called aerosol particles in meteorology, and PM2.5 is one of its measurement standards) that make up smog are easy to be accompanied by harmful substances such as heavy metals, which are popularly compared by experts as "a small stone and a small steel ball", and it is difficult for laser to penetrate.

on the other hand, in fact, as far as laser weapons are concerned, the current level in the world is also very limited (low power and short action distance). The transmission of laser in the atmosphere is not arbitrary, and it is necessary to select some wavelengths that are relatively easy to spread. However, factors such as fog, haze, aerosol particles and precipitation may absorb, scatter and refract the laser beam, thus seriously weakening its energy and greatly reducing its operational effectiveness.

under the influence of various factors, the laser beam with an initial power of 1, kilowatts will still reach the target surface with a power of 7,-9, kilowatts after being transmitted for 2 kilometers, but under some conditions, the target surface power may be only 2, kilowatts after being transmitted for 1 kilometers. If the intensity of turbulence and thermal halo in the air is moderate, the radius of laser spot on the target can be increased from 3.4 cm to 5 cm, which greatly weakens its destructive effect.

no matter the laser used for attack or the laser used for non-lethal purposes such as ranging, guidance, jamming and communication, from the day of its birth, it began to wrestle with the unfavorable transmission conditions in the atmosphere, which cost a lot of money and energy in terms of beam quality and adaptive compensation system. Especially for the aggressive laser system, this has even become one of the fundamental obstacles to its application.

However, everything has two sides. Smog is really "effective" in weakening the attack power of laser weapons, but it is more harmful to human health (I won't talk about it in detail)! Therefore, we must not completely focus on relying on "foggy days" to defend enemy laser weapons, which is neither scientific nor worthwhile.