I just flew to Chicago from Seattle and the flight was quite turbulent. I overheard a passenger saying it was because of “air pockets.” What is an air pocket?
Air pocket is a term from the early days of aviation, and it originally was applied to downdrafts because it caused an airplane to drop suddenly. Pioneering pilots imagined those downdrafts to be “pockets” in which there was insufficient air to support the plane. It is now known that localized downdrafts are a common occurrence, even in clear air. They can cause a rough flight even for today’s powerful jet aircraft.
In modern aviation terminology, an air pocket has three meanings: a local downdraft, an abrupt reduction of an aircraft’s headwind or an abrupt increase in its tailwind, all of which can cause the craft to drop suddenly.
Carolyn Szepanski sent us these pictures from Whiting, Indiana. She tells us:
I took a few pictures Sunday afternoon of the frozen fog crystals from Whiting, IN. The minute crystals were floating around in the air, like very fine ash, and left a pretty dusting on everything.
Thanks for the great shots Carolyn!
Photos courtesy of Carolyn Szepanski , Whiting, Ind.
Many thanks to Steve Newlin of Gurnee who snapped these incredible shots of the hoarfrost which coated the Devils Head Ski Resort in southern Wisconsin Sunday morning. They are beautiful! Thanks for sharing them with us Steve!
Val O’Sullivan and his son sent us these pictures from Rockton, Ill.
Josh Keating from bonfield, Illinois sent us these pictures of the freezing fog taken Sunday:
Claire Obrecht from Schaumburg sent us a shot of the scenery in Busse Woods:
Brittany Svee sent us these shots fromin Lockport, Illinois:
Dave Nikolai sent us these pictures from Wisconsin. He tells us:
“We woke up this morning to a decent accumulation of hoarfrost in Burlington, WI. .. The scenery was spectacular, especially when the sun broke through the fog about 11am. I was also able to capture a picture of a fogbow“
The past couple of mornings have featured a weather phenomenon that is not seen that often. Freezing fog has made for some nice “Kodak moments” but it can also create slick spots and make travel tricky. We might see more of it early tomorrow.
Remember that fog is basically a cloud near the ground. Water vapor in that cloud turns directly into ice crystals and forms on the surface or objects near the surface. It occurs when the air near the surface has dew points below the freezing mark. The result is called hoar frost.
For more discussion on freezing fog, check out:
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While there will be some periods of sunshine, cloudiness will prevail much of the week ahead over northeast Illinois. Today will start off similar to Sunday, with clouds, fog and haze trapped under a persistent low-level temperature inversion (temperatures increasing with height). Similar to Sunday, the heat given off in Chicago should help improve visibilities and allow some sun to break through, while areas away from the city under a thick snow cover will again be much slower to improve. Veteran weather observer Frank Wachowski reported the sun broke through late Sunday morning at Midway Airport, and his equipment actually recorded 369 minutes or 65 percent of the possible daily sunshine.
Until next weekend, low pressure will be holding south with Chicago on the northern edge of cloud cover and precipitation.
Storms hit the California coast
The first in a series of storms hit the California coastline Sunday with rain (and snow at higher elevations) overspreading that state. This week a 230 mph jet stream will repeatedly fling strong low pressure systems at that same area in 24- to 36-hour intervals. By the end of the week a total rainfall of 4 to 8 inches is expected along and immediately inland of the California coastline as well as into much of Arizona. The foothills could see from 10 to as much as 20 inches of rain with mudslides likely in recent burn areas. Above 5,000 feet, several feet of heavy snow along with 70 to 100 mph winds will slow travel to a crawl.