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.
