moon over trees








The above chart is generated from the Clear Dark Sky program developed by Canadian software engineer and amateur astronomer Attilla Danko. The color chips on the chart render the forecasts of a numerical weather model from Environmental Canada in easy-to-read, color coded format. It is perhaps the most accurate and practical forecast of astronomical observing conditions in North America.    A detailed description of the Bucknell Observatory Clear Sky Chart is provide here.   Here is a quick key to the colors:


Cloud Cover:
cloud_cover_color_chart_black

Transparency:
transparency_color_chart_black

Seeing:
seeing_color_chart_black

Darkness:

darkness_color_chart_black

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Clear Sky Charts - Clear sky forecasts for over 3,500 locations.

Weather Forecast for Astronomy - This site provides details on the numerical model developed by meteorologist Allan Rahill and used by the Environmental Canada to issue the above weather forecast for astronomy. In the clear sky above, the squares depict the hourly interval predictions for cloud forecast (row 1), sky transparency (row 2), seeing (row 3), in the upper group (labeled "sky") and the weather conditions near the ground (wind, humidity, and temperature) in the lower group (labeled "ground").