Weather Measure
Wednesday, August 29, 2007
Oregon Scientific Weather Radio Recall
 
Some radios could fail to receive National Weather Service alert signals in certain areas of the country. In the event of severe weather, this failure could put a consumer’s life and property at risk.

The recall involves the following models sold from December 2005 through June 2007:
• All Hazards Portable Weather Alert Radio (WR103NX)
• Portable Public Alert Radio (WR108)
• Public Alert Weather Station (WRB308)
• John Deere Public Alert Weather Station (WRB308J)

Contact Oregon Scientific for information on how to receive a free replacement radio.

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Thursday, May 24, 2007
Weather Sayings of the Old Sailors
 
Weather Sayings of the Old Sailors

• Dew indicates a good day ahead; a dry morning is sign of showers.
• Distant shores loom up "nearer" before rain because of thinning of the air.
• Large halo around the moon indicates cirrus cloudform and warm front rain.
• A veering wind is sign of fair weather; backing wind means rain.
• Falling barometer indicates nearing "low" area, with winds and rain.
• Rain is most frequent at the turn of the tide (if air is humid).
• Rainbow to windward, rain ahead. Rainbow to leeward, rains end.
• Higher the clouds, finer the weather. Lowering ceilings foretell a rain.
• Smoke that curls downward and lingers, means a nearing storm.
• Thinning air is harder to fly in. Birds "sit it out" before a storm.
• Sky full of webby cirrus foretells disturbance and rain's on its way.
• Lightning from the west or northwest will reach you; from south or southeast will pass.

Illustrations by Eric Sloane.

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Friday, May 4, 2007
Finding True North
 
Hints about orienting a wind vane to TRUE NORTH for accurate wind direction measurements

No matter how precise your electronic wind vane is, if the zero point of the wind vane's base is not oriented to north the readings will be in error.

There are some easy ways to find north. Once it gets dark look up into the sky and find the north star. When you have done that you are looking in the direction of true north.

Another aid can be our streets and roads. Many city streets are laid out in a north-south grid pattern. Just line the zero point of the anemometer so it points parallel to the north-south running streets.

The use of a compass to locate true north requires a little extra work. Magnet compass needles point to the magnetic north pole which is not at the same place as the geographic north pole. A correction must be applied to convert the magnetic north direction to the true north direction. The magnitude of the correction depends on where you are located. The following URL will take you to a U.S. government site that takes you through some very simple steps to convert magnetic compass readings to true direction readings for your location: http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

Once you have successfully aligned the anemometer to true north, your wind direction readings will report true wind directions within the limit of the errors of the anemometer.

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Tuesday, April 24, 2007
Why is it so windy in Reno?
 


Here is an interesting illustration from the Reno Gazette-Journal that explains why very high winds frequently blow in the valleys just to the east of the Sierra Nevada. The predominant wind blows from west to east over the Sierra Nevada and high winds aloft, associated with storms, spill down the lee side of the mountain range following the terrain. These winds of 50 mph or greater spill out onto the valley floors. Winds in the Washoe Valley south of Reno are frequently of sufficient strength to over turn large semi trucks and trailers. The drawing shows how this effect works. This kind of down slope gusting is not unique to the Sierra Nevada. Those of you who live along the Front Range of the Rocky Mountains are familiar with the same effect.

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Friday, April 13, 2007
Wind Direction Potentiometer Configuration
 
360° Format: For years a 360° potentiometer has been the standard for measuring wind direction. Because the resistance element of the potentiometer is roughly 358°, there is a "dead area" or "slot" of approximately 2°. This opening in the pot is customarily oriented to the north. The 360° format is extremely well suited to applications where a display indicator is used, either alone or with analog recording instrumentation. Its disadvantage is that when the wind is from the north readings will vary between maximum to minimum output as the wiper in the pot goes back and forth across the slot, thereby causing a pen trace across the full width of an E-A recorder or presenting numerous other complications for computer data logging.

540° Format: In recent years, a new configuration has been used quite successfully. Two potentiometers are joined together with wipers in the pots 180° from each other, thus providing a 540° uninterrupted display. This convention of dual potentiometers has greatly minimized the problems encountered in 360° displays. The signal conditioning provides automatic switching between the two pots.

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Friday, April 6, 2007
Algae Control in Evaporation Pans
 
evaporation pan

An evaporation pan must be cleaned frequently to keep it free from sediment, algae, and oil films. Any of these contaminants will materially affect the rate of evaporation.

The growth of algae can be discouraged by adding a small amount of copper sulfate to the water. (Approx 5-10 mg of copper sulfate per liter of water.) A standard Class A pan filled to 8 inches would require about 1/2 teaspoon of copper sulfate granules.

If algae is already present, it must be removed first by thoroughly cleaning the pan. Dry granules added directly into the pan will sink to the bottom and may not dissolve completely. If you have this problem, the granules can be dissolved in water before being added to the pan or placed in a burlap bag and dragged around the pan until dissolved.

It's not necessary to add additional copper sulfate each time you add water to the pan. The copper sulfate doesn't evaporate with the water but remains in the pan.

Copper sulfate is corrosive and can be toxic to animals and fish, so it must be handled with care and disposed of properly. Copper sulfate can be purchased at feed and agricultural supply stores, garden centers, and pet supply stores.

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Friday, March 30, 2007
Anticipating Severe Weather
 
NOAA Weather RadioNOAA Weather Radio All Hazards is a nationwide network of radio stations broadcasting continuous weather information directly from a nearby National Weather Service office. NWR broadcasts weather warnings, watches, and forecasts, and other hazard information, 24 hours a day. It is provided as a public service by the National Oceanic and Atmospheric Administration, part of the Department of Commerce, and includes more than 940 transmitters, covering all 50 states, adjacent coastal waters, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific Territories.

Skywarn is the spotter training program developed and sponsored by the National Weather Service. In areas where tornadoes and other severe weather is a frequent concern, the NWS recruits volunteers, trains them in storm identification and spotting procedures, and subsequently accepts the spotter's reports during episodes of severe weather.

Stormtrack megasite for storm chasers includes updates on weather-related events, training, and technology. You can find chase reports, discussion forums, humor, and links to meteorological resources.

StormReady - Some 90% of all presidentially declared disasters are weather related, leading to around 500 deaths per year and nearly $14 billion in damage. StormReady helps arm America's communities with the communication and safety skills needed to save lives and property.

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