Stories tagged meteorology
A prominent federal meteorologist has reversed his stance on global warming’s role in the recent increase in hurricanes. Tom Knutson, a researcher for the NOAA fluid dynamics lab in Princeton, has published a new paper in the journal Nature Geoscience predicting that Atlantic hurricanes will decrease by 18 percent by century’s end.
The new study is already brewing up a storm of its own because Knutson has complained in the past of being censored by the Bush administration for his previous views of climate change’s adverse effect on weather. Not surprisingly other researchers contend Knutson’s new computer models are flawed. Read the full story here.
Tags : Weather spotters needed
in Earth and Space Science, Scientific Inquiry, The Water Cycle, Weather and Climate, and Forces of Nature
Ever wanted to be a storm spotter? Now's your chance! The National Weather Service (NWS) relies on local SKYWARN storm spotters to confirm, from the ground, what meteorologists are seeing on radar. NWS storm spotters are not tornado chasers like the folks in the movie "Twister." Instead, they report wind gusts, hail size, rainfall, cloud formations, and the like to NWS and local emergency management agencies.
Tornado: This tornado, seen in its early stages of formation over Union City, Oklahoma (May 24, 1973), was the first one caught by the National Severe Storms Laboratory doppler radar and chase personnel. (Photo courtesy NOAA Photo Library, NOAA Central Library; OA
New radar equipment is still not sensitive enough to determine the existence of an actual tornado. It can only predict where severe weather is likely to occur. So the NWS needs trained volunteers to verify actual severe weather.
With peak storm season just around the corner (mid-June here in the Upper Midwest), free, 2.5-hour classes are being offered to train new SkyWarn volunteers.
SkyWarn class schedule, greater Minnesota
SkyWarn class schedule, Twin Cities Metro area
Rainbow: (Photo credit: Mark Ryan)
Living in Minneapolis, I often ride my bike for exercise around the city lakes. The other day, while trying to get a ride in between rain showers, I was presented with a stunning rainbow. Actually, only a small portion of the arc was visible when I first saw it at Lake Harriet, but by the time I reached the west side of Lake Calhoun it had grown into a full blown double arced rainbow.
I stopped to admire it and regretted not having my camera with me because it was truly one of the best rainbows I had witnessed in a long time. A kid next to me, snapping a picture of it with his cell phone, wondered out loud, “How far away do you think that rainbow is?”
It was a good question and made me want to learn more about the atmospheric phenomenon.
Raindrop refraction and reflection: Sunlight is refracted as it enters a raindrop, reflected inside, then refracted again as it exits. An observer sees only one color reflected from a particular raindrop.Graphic by Mark Ryan
Basically, rainbows are the result of sunlight being once reflected and twice refracted by raindrops. Certain conditions are required. First and foremost, the viewer needs to be located between the sun and rain clouds. A ray of sunlight enters an individual drop of water and is refracted (bent) as it enters, then reflected from the back of the drop, and refracted again as it exits the drop. The refractions cause the white sunlight to divide into separate colors. Each color refracts in slightly different amounts, red the least, and violet the most. A particular raindrop will reflect red light because it is positioned at just the right angle from your eye (42°). This is known as the “rainbow ray”. Another droplet located at a slightly different position will reflect blue light to your eye. Now multiply this by the innumerable suspended water droplets that make up a rain cloud, and you have a rainbow.
The main colors in a primary rainbow will have red at the top followed by orange, yellow, green, blue, indigo, and violet. An easy way to remember the order is to note that the first letter of each color spells out the name ROY G. BIV.
The rainbow I witnessed had a second, fainter rainbow just above the first. This is the result of some light being reflected twice, and at a higher angle. The colors in a secondary arc are reversed with red on the bottom and violet on top.
The inside of a rainbow is always brighter than the sky outside the arc. This is because other rays of light are reflected from individual raindrops at angles smaller than the rainbow ray. Since this scattered light is made up of all the other incidental colors the light inside the bow is white.
So, how far away is a rainbow? I’ll let you figure that out for yourselves. The answer may surprise you.
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