Fog can be a familiar phenomenon if you board a plane on a humid day.
The hot, humid air from outside meets the cold air inside blowing out from the air conditioning vents, temporarily creating fog inside the cabin, according to CNN. Two weeks ago, a TikTok user named Savannah Gowarty posted a video capturing fog on a domestic flight in the United States. The video garnered over 13.1 million views, with many viewers expressing surprise and confusion at what was happening. Experts say this is a natural phenomenon that lasts only for a short time and is nothing to worry about.
Fog appears briefly inside the airplane cabin. (Photo: Vajirawich Wongpuvarak/iStockphoto)
“On hot and relatively humid days, the cold air from the airplane’s air conditioning mixes with the warmer and more humid cabin air, causing its temperature to drop to the dew point, creating fog,” said a spokesperson from the Federal Aviation Administration (FAA).
When the plane is waiting to take off on the ground, the air inside the cabin is kept cool by the external air conditioning system or the aircraft’s auxiliary engine, according to the FAA spokesperson. Both provide cool air (which is often much cooler than the surrounding temperature), temporarily lowering the dew point of the air inside the cabin enough to create fog.
Climate scientist Indrani Roy from University College London stated that the environment inside the airplane creates perfect conditions for condensation to occur in the cabin. This is why the cabin surfaces appear damp. Condensation happens when water vapor in the air comes into contact with any cooler solid surfaces, and there are plenty of solid surfaces inside an airplane. Roy also emphasized that fog in the cabin is not a cause for concern.
However, even though the fog caused by humidity is completely safe, passengers sometimes remain anxious, especially when experiencing it for the first time, according to American flight attendant Rich Henderson. This is often because they mistake fog for smoke. For flight attendants, assessing when passengers need a scientific explanation is a skill they hone in their jobs, accumulating experience from daily interactions with various people. Anything unfamiliar to passengers can cause concern, such as unexplained noises or engine sounds.
According to the FAA spokesperson, fog in the airplane cabin typically dissipates very quickly. This is because the cooler air (which lowers the cabin air temperature to the dew point) rapidly warms back up to above the dew point. When this happens, the fog will disappear, often lasting only 1 to 2 seconds.
