 |
 |
|||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
  |
|||||||||
 |
||||||||||||
| ||||||||||||
|
Adam Skowronski, who has installed over 300 Davis weather stations in Poland for over the last ten years, sent us this frosty photo of a hard-working Vantage Pro2. It was taken on Kasprowy Wierch, a mountain of 6,519 feet (1,987 meters), in the Western Tatras of Poland. The mountain sits on the border of Poland and the Slovak Republic. The weather station is located on the mountain's famous and very popular cable railway's upper station. The building in the background is an astronomic observatory which also provides public meteorological services. (Click here to see the data from the station.) "This year, we have some interesting projects with Davis stations. We have been working on three systems: one for sailors,one for water treatment plants, and one warning system for drivers," Adam wrote. (What are those sideways Christmas tree things in the photo? Two Yagi antennae for Wireless Long-Range Repeaters with Solar Power!)
What's Our Favorite Weather Variable? (Oh, the Pressure of Choosing!) Brewster was a human-weather station: he had a bad knee that worked as well as any barometer in predicting an oncoming storm. When Uncle felt "all crickety and achy in the bones," he'd predict rain and he was usually right. Uncle also had a large-mouth bass weather station. The only chance he ever had of getting "Old Blue," the legendary monster of the local pond, to emerge from the depths to even nibble was when the atmospheric pressure was dropping. And then there was Aunt Ida's bird feeder weather station. It might be a lovely day, but if business was brisk at Aunt Ida's backyard feeding station, she'd assert that a storm was approaching. If Uncle's bad knee, Ida's birdseed, and Old Blue's activity all pointed to stormy weather, you didn't need a Vantage Vue or a highfalutin' meteorologist. A storm was coming. (Add one of Ida's "sick headaches" and you might as well just go ahead get out the umbrellas and rain gear right now.) What single meteorological variable were all of these weather-predictors probably responding to? Atmospheric pressure: possibly the best single variable for forecasting weather. Atmospheric pressure is, as we all know, the pressure exerted by the column of air that goes from the top of your head all the way into space. Air is light, yes, but a whole lot of light stuff can get heavy - almost 15 pounds per inch. (Don't worry, it won't squash you. The inside of your head is pushing right back, keeping your skull nice and round.) If you are, just by chance, standing on top of Mr. Everest, you've got a whole lot less air above your head. Since the earth's gravitation pull works just as well on the molecules of air as it does on spilled milk, there's not as much up there as down on the beach. The proportion of oxygen in the air is about 21%, by volume, wherever you are. But if there is less air, there is less oxygen. Hence the need for oxygen canisters on the way up to the summit. This means if we know the pressure, we know how much oxygen is available. It also means that if we increase pressure in an airplane cabin that is way up high where the pressure is low, we can increase the available oxygen. The most interesting thing about atmospheric pressure is not the absolute value or station pressure (which corrects for temperature, gravity and instrument error), at any point in time and space. It is the changes and comparisons that make it valuable. The little arrow on your Vantage Vue console, tilting downward, has more predictive value than the actual number. Like Uncle Brewster's aching knee, falling pressure is a good indicator of an approaching storm. The number is also valuable, but more as a comparative number rather than an absolute one. If we know the station pressures in San Diego and Denver, we really don't know all that much about the weather, because the folks in San Diego have a lot more air over their heads than those in Denver, so their station pressure is going to be higher. We need to correct both those readings for altitude so they read as if both stations were at mean sea level in order to compare them. (That's why, when setting up your console, you put in the elevation of your console.) The station pressure in Denver might be 894 mb, and the station pressure in San Diego might be 1000 mb, but adjust the Denver reading to sea level and they are almost the same. (The effect of altitude on atmospheric pressure allows pilots to measure it instead of dropping a measuring tape down to the runway to see how far above it the airplane is. Much easier.) Meteorologists can use mapped adjusted atmospheric pressure to see where high and low systems sit. The systems generally move from west to east, so we can use those maps to predict what will happen in the coming days. When a high pressure system approaches you from the west, you can "see" it coming by the subtle rise in pressure, followed by a drop as the system passes. You'll also see an increase in temperature, with a decrease when it passes, and a shift in wind direction. Approaching low pressure systems let you predict clouds and rain. Now that's a handy weather variable! Atmospheric pressure, besides causing headaches in aunts and boldness in fish, also
causes wind to blow, because, as anyone who has ever over inflated a balloon
knows, air moves from high pressure to low. It is affected by temperature
(cool air is more dense and therefore heavier; it sinks and pushes downward);
and humidity (more water vapor, less pressure). So that subtle change in your
barometric pressure encapsulates a whole lot of meteorological factors and
provides a whole lot of information. No wonder it is such a good indicator of
current and future weather.
>> Back to Menu
After upgrading the Macintosh WeatherLink software to v5.1.0, (you can upgrade all our software free on our web site) a small handful of customers have reported getting a Java error on startup. Typically, it is something like, "java.lang. Unsatisfied Link Error: nojspMacOSX in java.library.path..." This means that, for some reason, the program is not running in 32-bit mode. If this should happen to you, here's what you can do to ensure proper startup. 1. Use the Finder to find the WeatherLink application under Applications. 2. Click on the "more Info" button.
3. Make sure that "Open In 32-bit mode" is selected. Now your program should open without an error message.
>> Back to Menu Wind-Powered Car Goes Faster than the Wind Garth Bock was wandering around the internet recently, checking oil prices and studying up on wind-powered cars, when he saw a familiar friend in a photo! There's an interesting article on Wired.com about a wind-powered car that traveled directly downwind almost three times as fast as the wind! There's a photo of the very cool vehicle that looks like a racecar that crashed through a windmill and took some parts with it, and, what's that in the background? (How else could they verify the car went 2.86 times faster than the wind?) Thanks Garth!
>> Back to Menu
Bill Morris, of Morris, Illinois, (No they didn't name the town after him; we asked!) posted this photo on our Davis Facebook page. Just in case you have not yet checked out our Facebook Page and become a Davis fan, we'd thought we share it. Whee!
"No, I'm the King of the World!"
Four years ago, Barb Conine of Wrangell, Alaska, sent us a picture of a little male hummingbird on top of her Vantage Pro. "After that," Barb writes, "we never saw one do it again. Well, he's b...a...c...k! Probably a new bird but on the vane again. We were so excited to see him back again for the first time since May 2006. Back then you called it the bird ride at Disneyland and, gosh, here's another bird doing it." Must be fun; all the coolest birds and bugs are doing it.
Joan Peterson of Oakland, California was charmed by this view of the Orcas Island Eastsound Airport. The tiny airport serving the San Juan Islands of Washington boasts a comfortable waiting area, a big Coke machine for refreshment, and a nice weather station on the roof. What more could you want? (That's Joan's Kenmore Air jumbo jet you can see through the window.) Ann Nobles read about storing bottled water in our last issue. She just wanted to pass on some words to the wise from her personal experience: "I don't recommend storing gallons of bottled DHMO in original plastic containers (generic store brand) for months because the plastic may deteriorate just enough to spring a leak. In our case, we came in from work to find the kitchen floor wet from water dripping from the cabinet in which the bottled DHMO was stored. We now recycle empty four-liter glass wine jugs (Carlo Rossi Burgundy). They never leak and we have an unlimited supply. Dewar's glass bottles work well also, they just don't have as much capacity. Bonus -- any after taste is pleasant." (But how do you get those bottles empty, Ann? There must be a way.)
>> Back to Menu What do you think of the E-Newsletter? How can we improve? How do you use your Davis weather products? Email us at news@davisnet.com. Question 1: Pick the right definition. Scoring: >> Back to Menu Question 2: If air is only 21% oxygen, what is the rest? >> Back to Menu Question 3: What is the secret to getting the vehicle, going downwind, to go faster than the wind? Remove sail, add windmill. It's all about the apparent wind, on the blades of the windmill, not on the vehicle. Brainiacs, check out this discussion on Skepticblog.com >> Back to Menu Question 4: We asked, he answered. See if you can guess how he answered. Davis Weather Club E-News: Why were you sitting on Bill's wind vane? >> Back to Menu Question 5: Can mere mortals really turn wine into water, or vice versa? Yes.
>> Back to Menu Davis! What do you think of our new E-news format? Please continue to send your comments, weather URL's, and story suggestions to news@davisnet.com. We look forward to getting your comments and any responses you have to the Davis E-News. Member participation is what keeps the Davis E-News alive and kicking. Well, that's it for this edition. You'll be hearing from us again next month! The Davis Weather Club E-Newsletter is published by Davis Instruments. Vantage Vue, Vantage Pro2, Vantage Pro2 Plus, Vantage Pro, Vantage Pro Plus, Weather Monitor, Weather Wizard, WeatherLink, WeatherLinkIP, Weather Envoy, and Perception are trademarks of Davis Instruments Corp. |
||||||||||||
WEATHER IN ACTION
