Flight Over Denver Squeezed Snowflakes Out Of Clouds

Planes and precipitation typically don't mix well, leading to frustrating delays and violent turbulence. However, the roles can be reversed every so often. A flight landing in Denver, Colorado last Saturday night provoked light snowfall just by flying through cloud cover on its approach to the runway.

A single fight was responsible for the snowfall. United Flight 5528, a SkyWest Airlines-operated regional flight, was landing in the Mile High City after a two-hour, 30-minute flight from Williston Basin International Airport in North Dakota. While the snowfall was light and didn't accumulate into a measurable amount on the ground, it was certainly visible on weather radar. The patterns appeared like a neon-green smoke trail following the jet's approach. The Washington Post explained the phenomenon:

As the airplanes made final approach, they flew through a cloud of supercooled water droplets — or water droplets that remain liquid even at temperatures below freezing. That's because the droplets had nothing to freeze onto to become snowflakes — until the airplanes flew through.

Aircraft have inherently dirty combustion, with small amounts of microscopic particulates ejected out of the engines along with exhaust. Those itty-bitty specks of metal, hydrocarbons and sooty material can act as condensation nuclei, or embryos for water droplets to collect onto and freeze. The result? Lab-grown snowflakes of a sort, albeit unintentional.

The ejection of condensation nuclei into the atmosphere via airplanes is the same basic premise behind the idea of cloud seeding.

While cloud seeding isn't a new discovery, it's not as simple as United Flight 5528 makes it seem. A recent Government Accountability Office report detailed how government efforts burned money for 50 years attempting to seed clouds intentionally. The State of Utah is spending $12 million per year without significantly impacting the weather.