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Fog: the Malignant Weather Ninja

Although it is a common atmospheric phenomenon, there’s a reason that fog demands a pilot’s complete respect.

In some areas, fog is a nearly daily occurrence. [Shutterstock]
Gemini Sparkle

Key Takeaways:

  • Fog is defined as a low cloud reducing visibility (less than 5/8 sm) and forms when three conditions are met: condensation nuclei are present, the temperature and dew point converge, and light surface winds exist.
  • The article details seven distinct types of fog, identifiable by the acronym SURAPIF: Steam, Upslope, Radiation, Advection, Precipitation, Ice, and Freezing fog, each with unique formation processes and characteristics.
  • Types like Radiation and Advection fog are common and can significantly reduce visibility, with Radiation fog forming over land on clear, calm nights and Advection fog occurring when warm, moist air moves over a cooler surface.
  • Pilots, even those instrument-rated, must understand and respect fog's severe impact on visibility and adhere strictly to weather minimums to ensure aviation safety.
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Every pilot certificate and every rating you pursue will have a weather learning component to it. One of the most important concepts you cover is about clouds—how they are classified and formed and what their appearance means in terms of atmospheric stability.

I live in the Pacific Northwest, where fog—the lowest of the low clouds—is a nearly daily occurrence, especially in the fall and winter. I live close to the water, and on some days it never lifts. Other days, we get a few hours of flyable sunshine and visibility, and we watch the temperature and dewpoint spread very carefully because fog can sneak up on you ninja-like. And if you are not instrument rated and in an instrument-capable aircraft, instrument current, instrument proficient, and prepared to “go on the gauges,” you may have a really bad day. Know your enemy, as my father used to say.

Meg Godlewski

Meg Godlewski has been an aviation journalist for more than 24 years and a CFI for more than 20 years. If she is not flying or teaching aviation, she is writing about it. Meg is a founding member of the Pilot Proficiency Center at EAA AirVenture and excels at the application of simulation technology to flatten the learning curve. Follow Meg on Twitter @2Lewski.

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