Why Fog Can Beat a Laser Beam

Introduction

Laser weapons work by concentrating light onto a target long enough to heat, weaken, or damage it. Fog interferes with that process because the beam must travel through a cloud of suspended water droplets before it reaches the target. Even when a target remains visible to sensors or the human eye, fog can remove enough energy from the beam that the laser no longer delivers a useful destructive effect at the required distance. The result is a practical reduction in effective range rather than a simple on/off failure. Studies of atmospheric laser propagation consistently identify fog as one of the most challenging weather conditions because water droplets scatter and absorb laser energy far more strongly than clear air. [Springer+2SPIE Digital Library]link.springer.comMicrophysics and Optical Attenuation in FogMicrophysics and Optical Attenuation in Fog - Springer Natureby Q Wang · 2021 · Cited by 17 — For fog/mist conditions, the main a…

How Fog Droplets Scatter and Absorb Laser Light

Fog consists of vast numbers of tiny water droplets suspended in air. These droplets are often similar in size to the wavelengths used by many laser systems, placing propagation in the regime known as Mie scattering. In this regime, droplets redirect a significant fraction of the beam away from its intended path. Instead of arriving as a tightly concentrated spot, part of the energy is scattered in many directions. [Springer+2TopEx]link.springer.comMicrophysics and Optical Attenuation in FogMicrophysics and Optical Attenuation in Fog - Springer Natureby Q Wang · 2021 · Cited by 17 — For fog/mist conditions, the main a…

The problem is not merely that droplets sit in the beam’s way. Each droplet acts as a miniature optical obstacle. Across thousands or millions of droplets along the beam path, repeated scattering steadily reduces the energy that remains focused on the target. Some energy is also absorbed by the water itself and converted into heat within the fog rather than in the target. [Chinese Physics B+2ACP]cpb.iphy.ac.cndownload Article File.doChinese Physics BMultiple scattering and modeling of laser in fogby JY Xue · 2021 · Cited by 16 — When a laser is transmitted in fog, and…

Multiple-scattering effects can make the situation even worse. Light that has already been scattered by one droplet may encounter additional droplets and be scattered again, further reducing the useful beam intensity. Research on laser propagation in different fog types shows that attenuation depends strongly on droplet concentration, droplet size distribution, and fog density. [ResearchGate]researchgate.netResearch Gate(PDF) The Multiple Scattering of Laser Beam PropagationResearchGate(PDF) The Multiple Scattering of Laser Beam Propagation…January 10, 2023 — The laser beams were scattered and attenuated w…Published: January 10, 2023

For a laser weapon, what matters is not whether some light reaches the target. What matters is whether enough energy arrives in a sufficiently small spot to create rapid heating. Fog directly attacks that requirement.

Why Visibility Is Not the Same as Useful Energy Delivery

A common misconception is that if a target can still be seen through fog, a laser should be able to damage it. In practice, visibility and destructive energy delivery are different measurements.

Human vision and many imaging systems can operate with surprisingly small amounts of light. A laser weapon, by contrast, must deliver enough energy to heat material to damaging temperatures. The beam therefore needs far higher energy density at the target than a camera or observer needs for detection. [GAO]gao.govScience & Tech Spotlight: Directed Energy WeaponsScience & Tech Spotlight: Directed Energy WeaponsMay 25, 2023 — Directed energy weapons—such as lasers—use energy fired at the speed o…Published: May 25, 2023

This distinction explains why a target may remain trackable while laser effectiveness falls sharply. A beam that loses a moderate percentage of its power in transit may still illuminate the target, but the remaining energy may be insufficient to burn through a structure, damage electronics, or achieve the intended effect within the available engagement time. [Wikimedia Commons]upload.wikimedia.orgWikimedia CommonsHigh energy laser propagation in various atmospheric…by CR Fussman · 2014 · Cited by 25 — Laser dwell times for varyi…

Military analyses of high-energy lasers frequently emphasise that atmospheric extinction affects lethality disproportionately. A reduction in delivered power can force much longer dwell times—the period the beam must remain precisely on one point. As atmospheric losses increase, required dwell times can grow rapidly and eventually become operationally impractical. [Wikimedia Commons]upload.wikimedia.orgWikimedia CommonsHigh energy laser propagation in various atmospheric…by CR Fussman · 2014 · Cited by 25 — Laser dwell times for varyi…

What Wavelength Changes in Fog

Laser designers often try to improve atmospheric performance by selecting wavelengths that experience lower losses. This approach works to a degree, but fog remains difficult because droplet scattering can dominate propagation losses across a broad range of commonly used wavelengths. [MDPI]mdpi.comLight Transmission in Fog: The Influence of Wavelength on…by P Duthon · 2019 · Cited by 80 — A theoretical approach by calculating…

Research has shown that wavelength effects in dense fog are more complicated than the simple rule that “longer wavelengths penetrate better”. Some measurements and modelling indicate relatively small differences between certain near-infrared wavelengths in fog, while other studies show that attenuation can remain severe or even increase across parts of the infrared spectrum depending on droplet characteristics and fog structure. [ece.mcmaster.ca+2ResearchGate]ece.mcmaster.caComparison of laser beam propagation at 785 nm and…by II Kim · Cited by 1438 — It is more significant to say that these calculations s…

This means wavelength selection can improve performance at the margins, but it cannot eliminate the underlying problem. Fog is fundamentally a collection of water droplets large enough to scatter substantial amounts of laser energy regardless of careful wavelength choice. [Springer]link.springer.comMicrophysics and Optical Attenuation in FogMicrophysics and Optical Attenuation in Fog - Springer Natureby Q Wang · 2021 · Cited by 17 — For fog/mist conditions, the main a…

Why Range and Dwell Time Shrink in Fog

The practical consequence of fog is a shrinking engagement envelope.

As range increases, the beam encounters more droplets. Every additional metre of fog increases cumulative scattering and absorption. The relationship is often unforgiving: a target twice as far away may experience substantially more attenuation because the beam has traversed a longer path through the obscuring medium. [SPIE Digital Library]spiedigitallibrary.orgThe laser transmittance is 40% in the 100mSPIE Digital LibraryAnalysis research on transmitting and attenuating…In this paper, the influence of fog visibility of laser attenuat…

At the same time, the laser must maintain damaging energy on the target for a longer period. If atmospheric losses reduce the power arriving at the target, the dwell time required to achieve damage rises. Modelling of high-energy laser engagements shows that worsening visibility conditions can dramatically increase required dwell times and reduce viable engagement distances. Eventually, the target may move, manoeuvre, rotate, or leave the engagement window before sufficient heating occurs. [Wikimedia Commons]upload.wikimedia.orgWikimedia CommonsHigh energy laser propagation in various atmospheric…by CR Fussman · 2014 · Cited by 25 — Laser dwell times for varyi…

This is why laser range in fog cannot be described by a single fixed number. The useful range depends on fog density, target vulnerability, beam power, wavelength, and the amount of time available to keep the beam on the target. [GAO+2Elib DLR]gao.govScience & Tech Spotlight: Directed Energy WeaponsScience & Tech Spotlight: Directed Energy WeaponsMay 25, 2023 — Directed energy weapons—such as lasers—use energy fired at the speed o…Published: May 25, 2023

Can Technology Overcome the Problem?

Modern laser programmes use adaptive optics, beam-control techniques, atmospheric sensing, and wavelength optimisation to improve performance under degraded conditions. Military developers have repeatedly argued that lasers are not rendered completely useless by fog, rain, or dust. [Army+2ResearchGate]army.mildeveloping lasers that pierce fog dust to destroy targetsArmy developing lasers that pierce fog, dust to destroy targets23 Oct 2017 — A lot of people think that high-energy lasers, or HELs…

However, these technologies mainly reduce penalties rather than remove them. Atmospheric attenuation remains a fundamental propagation challenge for directed-energy systems. Recent research has even explored exotic approaches such as using ultrashort laser pulses to clear channels through fog by physically disrupting droplets, illustrating how significant the fog problem remains. [arXiv+2arXiv]arxiv.orgarXiv High repetition rate ultrashort laser cuts a path through fogHigh repetition rate ultrashort laser cuts a path through fogDecember 25, 2016…Published: December 25, 2016

The key point is that fog does not have to stop a laser completely to defeat it operationally. If enough energy is scattered or absorbed that the target cannot be damaged within the required range and time, the weapon’s effective reach has already been shortened. That makes fog one of the most important atmospheric limits on high-energy laser weapons. [Springer+2GAO]link.springer.comMicrophysics and Optical Attenuation in FogMicrophysics and Optical Attenuation in Fog - Springer Natureby Q Wang · 2021 · Cited by 17 — For fog/mist conditions, the main a…

Amazon book picks

Further Reading

Books and field guides related to Why Fog Can Beat a Laser Beam. Use these as the next step if you want deeper reading beyond the article.

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Introduction to adaptive optics

By Robert K. Tyson

First published 2000. Subjects: Adaptive Optics, Optical detectors, Optical instruments, Optical measurements, Optics, Adaptive.

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Fundamentals of Photonics, 2 Volume Set

By Bahaa E. A. Saleh, Malvin Carl Teich

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Directed Energy Weapons

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First published 2016. Subjects: Lasers.

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Laser Beam Propagation through Random Media

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Directly addresses how atmospheric conditions degrade laser performance.

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Browse more on Amazon: to adaptive optics books Fundamentals of Photonics, 2 Volume Set Directed Energy Weapons

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Endnotes

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2. Source: gao.gov
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   Published: May 25, 2023

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    (PDF) Wavelength and altitude dependence of laser beam...13 Jan 2015 — Our results show that an atmospheric attenuation in such fogs sli...

11. Source: army.mil
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12. Source: researchgate.net
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    mitigated through feedback from wavefront and atmospheric sensors to the adaptive...Read more...

13. Source: arxiv.org
    Title: arXiv High repetition rate ultrashort laser cuts a path through fog
    Link: https://arxiv.org/abs/1612.08276
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    High repetition rate ultrashort laser cuts a path through fogDecember 25, 2016...

    Published: December 25, 2016

14. Source: arxiv.org
    Title: arXiv Atmospheric aerosol clearing by femtosecond filaments
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    Title: arXiv Free space laser telecommunication through fog
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    Title: The laser transmittance is 40% in the 100m
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Additional References

1. Source: eureka.patsnap.com
   Title: report atmospheric effects on long range [laser power]({{ ‘power-costs/’ | relative_url }}) transmission
   Link: https://eureka.patsnap.com/report-atmospheric-effects-on-long-range-laser-power-transmission
   Source snippet

   Effects On Long-Range Laser Power...28 Aug 2025 — Weather conditions dramatically affect transmission efficiency, with fog, rain, snow...

2. Source: c4isrnet.com
   Title: cloudy and a chance of rain need not sideline high energy lasers
   Link: https://www.c4isrnet.com/opinion/2018/02/26/cloudy-and-a-chance-of-rain-need-not-sideline-high-energy-lasers/
   Source snippet

   Cloudy and a chance of rain need not sideline high-energy...Feb 26, 2018 — As such, while certain effects of a laser weapon are negative...

3. Source: deps.org
   Link: https://www.deps.org/DEPSpages/JDE/JV2N4P6-Fiorino.pdf
   Source snippet

   ible to the shortwave infrared, with the exceptions again of 1.31525 µm, which...Read more...

4. Source: laserwars.net
   Title: navy laser weapons challenges atmosphere fog
   Link: https://www.laserwars.net/p/navy-laser-weapons-challenges-atmosphere-fog
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   Fog of War: The Biggest Challenge for Naval Laser Weapons22 May 2025 — Welcome to the literal fog of war, where high-energy lasers run fa...

   Published: May 2025

5. Source: ciaotest.cc.columbia.edu
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   Energy Weaponsby CN Ghosh · Cited by 9 — Laser beam can get degraded if there is fog, cloud or rain but it does not affect the PBW...

6. Source: youtube.com
   Title: How Lasers Might Control the Weather: Real Science
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   【Photonics Innovation】How Lasers Might Control the Weather: Real Science - YouTube 【Photonics Innovation】How Lasers Might Control the Wea...

7. Source: youtube.com
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   ectromagnetic energy, and include lasers, high-powered [microwaves]({{ 'microwaves/' | relative_url }})...

8. Source: youtube.com
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   How Lasers Might Control the Weather: Real Science...

9. Source: youtube.com
   Title: Laser Weapons Are Becoming Reality Faster Than You Think
   Link: https://www.youtube.com/watch?v=knCuGgPkZ-4
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   Eurosatory Day 2: Laser Weapons Go Operational & France Unveils B-Strike Missiles...

10. Source: defencesciencereview.com.pl
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    DEFENCE SCIENCE REVIEWby A Karkadakattil · 2026 · Cited by 1 — This review aims to evaluate the current capabilities of laser- based Dire...