Interesting fact: A cubic meter of fog often holds less liquid water than a teaspoon, even when visibility looks terrible.
The answer: Fog usually contains about 0.05 to 0.5 grams of liquid water per cubic meter of air. That means a cubic meter of fog weighs only a fraction of a gram more than the same cubic meter of clear air.
Fog is difficult to weigh because most of its mass is still ordinary air, while the suspended droplets add only a tiny extra amount. Scientists measure fog water content with collectors, sensors, and droplet studies rather than a simple scale. Its weight matters in aviation, road safety, water harvesting, and climate research because even a little liquid water can change visibility dramatically.
