Weather Measure
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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Friday, March 23, 2007
Power Budget Calculations
 
The power budget is an analysis of how much power a data collection site requires. The analysis is required to determine how long a data recorder or a remote telemetry unit (RTU) will operate from a battery of a given capacity (amp-hours) without recharging and what size solar panel (or charging source) should be used to sustain the battery.

A power budget is determined by calculating how much time a data recorder or RTU spends in each of its operating modes and then summing the power used in each mode.

You can see an example of a power budget calculation here.

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Thursday, March 15, 2007
What Is a Wind Rose?
 
The wind rose is the time honored method of graphically presenting the wind conditions, direction and speed, over a period of time at a specific location. To create a wind rose, average wind direction and wind speed values are logged at a site, at short intervals, over a period of time, e.g. 1 week, 1 month, or longer. The collected wind data is then sorted by wind direction so that the percentage of time that the wind was blowing from each direction can be determined. Typically the wind direction data is sorted into twelve equal arc segments, 30° each segment, in preparation for plotting a circular graph in which the radius of each of the twelve segments represents the percentage of time that the wind blew from each of the twelve 30° direction segments. Wind speed data can be superimposed on each direction segment to indicate, for example, the average wind speed when the wind was blowing from that segment's direction and the maximum wind speed during the logging period. A good example of a wind rose application is shown at the following URL http://www.wcc.nrcs.usda.gov/climate/windrose.html. Another
site that has some interesting wind rose information and a simple program for generating a wind rose is http://www.windpower.org/en/tour/wres/rose.htm.

The information provided by the wind rose can be applied to many and varied situations. Sailors use wind rose information taken from the "Pilot Charts" by the U.S. Naval Oceanographic Office to get average winds for each ocean for each month of the year to help the create optimal sailing routes between ports. Architects do, or should, use wind rose information for the siting of buildings and stadiums. If wind rose data had been collected and used prior to the construction of San Francisco's famous windy Candlestick Park, the stadium could have been placed a few hundred yards to the north where it would have been protected from the prevailing westerly wind. Windpower "farms" do extensive wind rose type studies prior to erecting their wind turbines. Thus the wind rose is a simple information display technique that has a multitude of uses.

More wind rose links

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