It was snowing south of Dallas earlier this week but don’t blame the weather, at least not entirely. The area under the southern extended centerlines of the Dallas-Fort Worth International Airport’s four main parallel runways got a dusting of snow thanks to a phenomenon known as airplane-effect snow, according to the Washington Post. Under the right circumstances, including a sharp temperature inversion, water vapor from the engines becomes supercooled and nucleate on the tiny bits of soot coming from the engines and form snowflakes, which then drop on weather-weary people below. It’s a rare phenomenon but virtually unheard of as far south as Dallas.
However, much of Texas joined the entire central portion of the country under a more generous than usual export of Arctic air from Canada. It’s a dry cold that doesn’t produce snow but the jet exhaust provided the missing ingredients. It was about 24 degrees Fahrenheit on the ground during the surprise snowfall. A similar snowfall was reported in Oklahoma and there was also lake-effect snow, a similar phenomenon, near Tulsa, the Post reported. In case residents can’t tell the difference, up to 10 inches of the regular stuff is forecast to fall by Monday and the temperature won’t get above freezing until next Friday.
It’s contrails at very low altitude. 😉
Will vary with aircraft type as newer engines produce less soot.
(Probably no original KC-135s and B-52s still flying, smoky machines. nor 747s with water injection for takeoff.
USAF et all hung onto the turbojets for a pitifully long time, I saw one on display at the Abbotsford Air Show decades ago.
Both types still in operation with turbofans of 707B vintage, but some KC-135s re-engined with CFM-56 engines as in B737-300, and now the KC-46A replacement based on B767 design is sort of in service. And USAF is thinking about re-engining B-52s with a one-for-one replacement engine, having been too cheap to accept lease of B757 engines from Pratt and Rolls. (Which would require new pylon and supporting structure to change from eight to four engines. The change would have eliminated need for refueling logistics for strike missions deep into enemy territory.)
B747s moved on from water injection as engine makers finally came up with higher thrust engines like the JT9D-7Q.
Water injection is tough on engines.
Factoid: On one demo of increased takeoff weight, a Boeing flight test became 6,000 pounds lighter during the takeoff roll, due consumption of water.
Error: the linked article incorrectly refers to particles in the exhaust as ‘metallic’ when in fact they are carbon.
(Best not be metallic, that would mean the engine is wearing rapidly.)
Well, it is WaPo, quality as poor as Jeff Bezos’ other operation – Amacrick makes mistakes but is very difficult to contact to fix problems.