The 2007 Atlantic hurricane season officially begins June 1 and runs through November 30.
Check back often for the latest predictions, forecasts, and discussion.
A story in the New York Times this week is providing more evidence about “super snowflakes.”
For ages artists and writers have waxed poetically about huge flakes of snow. Hollywood movie producers and Hallmark card creators have used those images to depict winter. But they’re just figments of our imagination, right?
Hard scientific data is now being collected about the size of snowflakes, the researchers doing that work have been pleasantly surprised. They’ve found that snowflakes measuring from 2 to 6 inches wide regularly fall around the world. Some reports about the “super flakes” say that they’re so large – the size of saucers or plates – that their edges turn up and centers sag due to their weight.
A snowflake expert from the California Institute of Technology points out that there’s scientific basis that limits the size of snowflakes. But, he points out, large snowflakes may often break apart due to the pressures from high winds hitting them as they fall to the Earth.
For ages, scientists had never really measured the size of snowflakes. But on some recent research trips, researchers have seen snow falling that measured two or three inches in size. That’s spurred on more interest – and research – into the size of snowflakes.
In the future, some of that research may be done from space. NASA will be launching a global satellite in 2013 that will monitor global precipitation patterns. That technology will be able to gauge the moisture in each rain or snow fall, along with the size of the flakes falling.
It's cold this morning. Maybe the coldest morning of the season so far? Luckily, there's also a lot of sunshine, and almost no wind.
If it were windy, you'd hear the weather forecasters talking a lot not only about the air temperature (-6 degrees when I left the house), but also about the "wind chill." Wind chill is a way to describe how quickly heat is transferred from your body to the atmosphere when it's both cold and windy outside. As wind increases, more heat is drawn from your body, decreasing your skin temperature and eventually your internal body temperature. Wind chill makes it feel much colder than it actually is.
Last year, I overheard a woman in the Science Museum parking garage elevator talking about how she parks her car in a sheltered area to protect it from wind chill. She was worried that, if she left it in a more exposed area, it wouldn't start. I can't say anything about the state of her car battery, or condensation on her distributor, but I can say that wind chill has very little impact on cars or any other inanimate objects: wind will shorten the time it takes for an object to cool to the temperature of the surrounding air, but it won't get any colder than that no matter how much wind there is.
For humans and animals, though, wind chill affects how quickly hypothermia and frostbite can occur. Hypothermia is a condition in which core body temperature has fallen to the point where normal muscle and brain functions are interrupted. (Thor did a post about hypothermia a few weeks ago.) Frostnip/frostbite are conditions in which body tissues freeze. Knowing the wind chill helps us make decisions to avoid these and other cold weather dangers.
The best thing to do when there's a significant wind chill is to stay inside. But you can't stay at home on the sofa all winter. So what can you do? Dress right when you go outside. That means wearing several layers of loose-fitting, lightweight, warm clothing. (Trapped air between the layers will insulate you and keep you warm.) Stay dry. (Remove layers if need be to avoid sweating and later being wet and cold.) Wear a tightly woven, water repellent, hooded top layer. Cover your mouth to protect your lungs from the cold. Mittens, which allow your fingers to share warmth, are better than gloves. And your mom was right: wear a hat! Half your body heat can be lost from your head.
Will Bing Crosby be singing the blues this year?
He, along with anyone else hoping for a White Christmas, might want to check out this probability map for the chances of having a white Christmas in the United States. As you can see, Minnesota and the upper Midwest are among the prime locations to have a white Christmas.
U.S. weather records averaged over a 30-year period show that only five places with long-term weather records are practically guaranteed to have a white Christmas. They are Marquette and Sault Ste Marie in Michigan, Hibbing and International Falls in Minnesota, and Stampede Pass in Washington.
As the map shows, wide areas of northern Minnesota and Wisconsin, much of Michigan's Upper Peninsula, and western mountains including the Cascades of Washington and Oregon, California's Sierra, and the Rockies from Montana and Idaho south into southern Colorado have a better than 90% chance of snow on the ground at Christmas.
Of course, from year to year the weather varies. There’s never a guarantee of a having a white Christmas. How important is it to you to have a snow during the holidays?
Roger Ledding, former chief of the Minnesota State Patrol, was on WCCO radio this morning, talking about the high number of traffic accidents during today's am rush hour.
No snow, no ice, so what's the problem?
Well, it's been very dry in the Twin Cities lately. A fine spray of oil from cars routinely covers road surfaces. In very dry weather, that oil can build up. When rain begins to fall, it mixes with the oil and the road surface becomes extremely slippery. It can take a few hours for additional rain to break down and wash away the mess.
Also, this morning's wasn't a gentle, soaking rain, but a downpour. That left standing water on roadways. Drivers traveling too fast found themselves hydroplaning--sliding on a thin film of water, unable to stop or steer.
It's been unseasonably warm, for sure, and I wasn't thinking about hazardous driving conditions on my way in to work this morning. But I will be on the way home...
The Minnesota Daily is featuring stories about how climate change could affect Minnesota's north woods. The speakers featured in the article talked with a crowd of over 100 here at the Science Museum of Minnesota last night.
Storm chasers know that puffy cumulus clouds often cause sudden rainstorms, while storms associated with stratus clouds form more slowly. Now physicists at England’s Open University have finally found an explanation.
They propose that neighboring water droplets in a stable stratus cloud don’t crash into each other because they’re all moving at about the same speed. But fast-forming, turbulent cumulous clouds contain water droplets moving at many different speeds. They crash into each other and form larger drops. As the turbulence grows, the drops grow quickly and fall as rain within a few minutes.
Sun and rain
Ever noticed the bright, moving lines on the bottom of a stream, bathtub, or swimming pool? They’re called caustics, and they’re caused when ripples on the water’s surface focus sunlight. (Caustics form whenever light rays are bent by a curved surface or object and then projected onto another surface.
Caustics have a characteristic shape. Physicists can graph the phenomenon mathematically, and the graph also describes other phenomena, such as particle motion or the movement of raindrops within a cumulus cloud.
Atmosphere to outer space
The researchers say their finding won’t have any impact on weather forecasting. But particle collisions in turbulent gases must have been involved in planet formation. Perhaps the same theory can be applied?
If you're at the museum on Saturday afternoon (11/18), the MakeIt team can help you play with caustics. Does bending mylar in a different direction produce a new pattern? Does using a different color flashlight or a brighter or dimmer light affect the design?
You can also play with caustics at home.
NASA scientists spent a month flying a sensor-packed airplane into storms brewing off the western coast of Africa. Data collected from these missions might someday allow better storm prediction and forecasting, and will definitely contribute to our knowledge of how hurricanes form and sustain themselves.
There's been a rash of cool weather sites written up in the Twin Cities newspapers and other media lately.
Here are just a few:
Skeetobiteweather is one of the most popular hurricane sites run by amateurs. Jonathon Grant, of Lakeland, Florida, runs it. He says the site gets 1.8 million page views a week, and you can plug in your zip code and get a prediction of wind forces for your block, hour-by-hour, before a hurricane hits. (Not even the National Weather Service does that.) And pretty soon, you'll be able to enter your exact address.
Mark Sudduth, of Wilmington, North Carolina, runs HurricaneTrack and HurricaneLiveNet. He deploys several battery-powered, waterproof cameras at the exact points where hurricanes are expected to hit. He also collects weather data to accompany the live, streaming video.
Jesse Bass, of Hampton Roads, Virginia, is a weather chaser who posts photos and commentary on his website, VAStormPhoto.
HurricaneCity, despite its name, is one of the more comprehensive severe weather sites. Jim Williams, of Delray Beach, Florida, focuses on the city being hit, and you can see all live, streaming radio stations or TV from the site. He also has a towercam on his roof, which captured images from Hurricane Wilma last year, and he hosts "The Hurricane Warning Show" from his living room.
Mike Watkins, of Coconut Creek, Florida, covers Atlantic hurricane action on TropicalUpdate. And if there's no news on the hurricane front, he hosts an Internet radio show where he interviews the "celebrities" of the weather world--guys like Max Mayfield, of the National Hurricane Center, or William Gray, the Colorado State University professor who's known for his hurricane season forecasts.
A new study found a link between human use of fossil fuels and an increase in the severity of hurricanes. The burning of fossil fuels has increased the level of greenhouse gases in the atmosphere, which has led to the warming of oceans in regions where hurricanes develop. The warmer the ocean water, the more severe the hurricane.