Very Cool Science: Airplanes Landing In Chicago Are Causing It To Snow

With temperatures below freezing and saturated air (high relative humidity) aircraft descending to land can cause snow. It’s a very localized event, not widespread snow, but snow can form and then fall as a result of planes descending under the right conditions.

This requires “supercooled atmosphere interacting with exhaust” and “water vapor [that is] below freezing but [that] couldn’t entirely transition into ice crystals because of a lack of particulates upon which to freeze.” Then the plane descending through the atmosphere causes snow to form.

There are a couple potential causes. One is that the aerosols, soot, sulfates and hydrocarbons engines spew act as tiny nuclei for snowflakes to form. The other is that lift around the wing causes ice crystals to form, seeding the air in similar fashion.

This phenomenon actually happened last week, and was noticed by the National Weather Service Chicago – localized snowfall from planes landing at both O’Hare and Midway airports.

This is some pretty cool science, but no doubt will span chemtrail conspiracy theories and other theories of how human activity controls the weather.

About Gary Leff

Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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  1. Less worried about chemtrail conspiracy than I am NIMBYs who’ll use this as another arrow in their crusade against airlines.

    >you caused it to snow! I’m suing!

    >This car accident is your fault!

    ad nausem

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