Clear Sky Chart

Clear Sky Chart

Clear Sky Charts (called "clocks" until 2008-02-29) are web graphics which deliver weather forecasts designed specifically for astronomers. They forecast the cloud cover, transparency and astronomical seeing, parameters which are not forecast by civil or aviation forecasts[1]. They forecast hourly data, but are limited to forecasting at most 48 hours into the future. Each individual chart provides data for only a 9 mile radius, and so are essentially point forecasts. There are clear sky chart forecasts for over 4000 locations, though the coverage area is limited to Canada, the USA and parts of Mexico and the Caribbean. Locations are typically cities, professional and public observatories, colleges and science centers. However there are also clear sky charts for star parties and backyard observatories.

Sample image of a clear sky clock for one particular observatory.

Contents

History

In 2000, Allan Rahill, a meteorologist at the Canadian Meteorological Centre (CMC), created a forecast processing step that took data from CMC's Global Element Multi-scale (GEM) forecast model and created a new forecast of cloud cover[2]. Rahill specially designed his cloud forecast to consider the formation of cirrus clouds. The cirrus cloud modeling distinguishes Rahill's model from other cloud forecast models, as sufficient cirrus clouds to make a night unusable for astronomers is still called "clear" by civil weather forecasts.

In later years, Rahill added a forecast of astronomical transparency, which is a measure of how much starlight traverses the Earth's atmosphere when otherwise free of clouds. Rahill also added a forecast of astronomical seeing which uses forecast data of turbulence and temperature gradients in the atmosphere to forecast its optical steadiness.

In 2001, Attilla Danko, computer programmer and amateur astronomer, began to summarize Rahill's hundreds of forecast maps by displaying only one pixel, from each map, laid out in rows[3]. The resulting meteogram, called a clear sky chart, showed all of Rahill's forecast data, but for only one location. Danko writes "It shows at a glance when, in the next 48 hours, we might expect clear and dark skies for one specific observing site". Danko accepts requests from observatories and private individuals to create new CSCs for locations not currently covered[4]. However, since CMC's GEM model only covers North America, CSCs are limited to North America.

Name change

On February 29, 2008 Danko changed the name of the CSCs to "clear sky charts" to avoid any possibility of legal action on the part of Skyclock company of Michigan who owns a USA registered trademark on the name "SKYCLOCK"[5]. Danko's attorney opined that he was not infringing Skyclock Company's trademark, but also advised that changing the name was the "least painful" and least "expensive" solution[6]. However, there continue to be references to the old name on web sites not controlled by the domain cleardarksky.com.

Recognition

Rahill and Danko have received awards from meteorological and astronomical organizations:

Since the clear sky charts terms of use permit non-commercial web sites to display clear sky chart images, they are most commonly recognized by private and club astronomy websites in North America.

References

  1. ^ A. Danko., "'A Weather Clock for Observers'", Sky and Telescope Apr 2003; 62; [1]
  2. ^ *Ivan Semeniuk., "STARSTRUCK: Clear Sky Clock", Daily Planet, Discovery Channel. April 15, 2005
  3. ^ Lydia Lousteaux., "'Interview with the creators of the Clear Sky Clock'" astronomytoday.com; [2]
  4. ^ "The Clear Sky Clock" Sky News magazine. #54 | Volume IX, Issue 6 | March/April, 2004
  5. ^ "'Clear Sky Chart FAQ: Why the name change?'"; cleardarksky.com;
  6. ^ "'Clear Sky Chart News'"; Feb 29, 2008; cleardarksky.com;
  7. ^ http://www.astrosociety.org/membership/awards/10winnerspub.html
  8. ^ CMOS Prizewinners 2004 / Lauréats des prix de la SCMO, 2004
  9. ^ Tim Cole., Astronotes August 2005
  10. ^ TSP History
  • "A Weather Clock for Observers". A.Danko. Sky & Telescope Magazine; Apr 2003; 62;
  • "The Clear Sky Clock" Sky News magazine. #54 | Volume IX, Issue 6 | March/April, 2004
  • "Interview with the creators of the Clear Sky Clock" Lydia Lousteaux. astronomytoday.com http://www.astronomytoday.com/astronomy/interview7.html
  • "STARSTRUCK: Clear Sky Clock", Ivan Semeniuk'. Daily Planet, Discovery Channel. April 15, 2005
  • "Weather Resources on the Internet", Observer's Handbook 2008, pp78–82, Royal Astronomical Society of Canada http://www.rasc.ca/handbook/
  • "How We Really Predict Clouds" Danko, A., Journal of Irreproducible Results, 2006, VOL 50; NUMB 1

External links


Wikimedia Foundation. 2010.

Нужно сочинение?

Look at other dictionaries:

  • Clear Sky Lodge Airport — IATA: CLF – ICAO: none – FAA LID: CLF Summary Airport type …   Wikipedia

  • Clear (Scientology) — Description A condition in which Scientologists say a person is free of the influence of unwanted emotions and memories of trauma Early proponents L. Ron Hubbard Key texts Hubbard s Dianetics: The Modern Science of Mental Health (1950) Subject… …   Wikipedia

  • On a Clear Night — Studio album by Missy Higgins Released 28 Apr …   Wikipedia

  • Spirit in the Sky — Single infobox | Name = Spirit in the Sky Artist = Norman Greenbaum from Album = B side = Released = 1969 Format = 7 Recorded = 1969 Genre = Rock Length = 3:57 Label = Reprise Records Producer = Erik Jacobsen Chart position = 3 Billboard 1 UK… …   Wikipedia

  • Blue Sky Mining — Infobox Album | Name = Blue Sky Mining Type = Album Artist = Midnight Oil Released = February 25, 1990 Recorded = 1989 in Sydney Genre = Rock Length = 46:52 Label = Columbia Producer = Warne Livesey Midnight Oil Reviews = * Allmusic Rating|4|5… …   Wikipedia

  • It Came Upon the Midnight Clear — is a poem and Christmas carol written by Edmund Sears, pastor of the Unitarian Church in Weston, Massachusetts. [http://www.cyberhymnal.org/bio/s/e/sears eh.htm] It first appeared on December 29, 1849 in the Christian Register in Boston.… …   Wikipedia

  • Under a Blood Red Sky — Infobox Album Name = Under a Blood Red Sky Type = live Artist = U2 Released = November 1983 Recorded = 6 May 1983 – 20 August 1983, Effanel Mobile Genre = Rock Length = 35:29 Label = Island Producer = Jimmy Iovine Reviews = *Allmusic Rating|3.5|5 …   Wikipedia

  • Amateur astronomy — Amateur astronomy, a subset of astronomy, is a hobby whose participants enjoy studying and observing celestial objects. Overview The typical amateur astronomer is one who does not depend on the field of astronomy as a primary source of income or… …   Wikipedia

  • Cherry Springs State Park — Coordinates: 41°39′46″N 77°49′23″W / 41.66278°N 77.82306°W / 41.66278; 77.82306 …   Wikipedia

  • Chamberlin Observatory — Chamberlin Observatory, circa 1900. Or …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”