Lake Taghkanic State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Taghkanic State Park clear sky chart from 2005-11-05 to 2008-12-24.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	17% 6% 5% 5% 6% 5% 7% 32%	12475
	Night	18% 6% 5% 5% 6% 5% 6% 33%	12519
Cloud Cover	Day	17% 6% 5% 5% 6% 5% 7% 32%	12491
	Night	18% 7% 5% 5% 6% 5% 6% 33%	12545
Transparency	Day	9% 19% 25% 13%	8576
	Night	9% 19% 25% 14%	8834
Seeing	Day	12% 28% 26% 17%	783
	Night	17% 35% 27% 6%	3573

By Month

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	17% 5% 5% 10% 6% 5% 6% 29%	752
	Night	19% 8% 5% 5% 6% 5% 5% 6% 28%	1288
February	Day	14% 6% 6% 8% 9% 7% 7% 26%	782
	Night	14% 8% 6% 5% 7% 8% 6% 5% 7% 24%	1009
March	Day	14% 8% 6% 6% 5% 5% 5% 36%	984
	Night	17% 5% 5% 7% 7% 6% 35%	1012
April	Day	22% 6% 5% 5% 6% 36%	1090
	Night	18% 6% 5% 5% 5% 5% 5% 35%	887
May	Day	19% 5% 5% 6% 5% 6% 6% 32%	1273
	Night	22% 5% 5% 5% 7% 35%	775
June	Day	19% 5% 5% 7% 6% 6% 9% 26%	1251
	Night	16% 5% 5% 5% 6% 7% 8% 32%	718
July	Day	11% 5% 6% 9% 6% 6% 11% 30%	1301
	Night	16% 7% 6% 7% 9% 32%	740
August	Day	11% 5% 5% 6% 6% 5% 5% 8% 38%	1160
	Night	12% 5% 5% 5% 6% 6% 5% 6% 39%	872
September	Day	15% 5% 8% 44%	1033
	Night	16% 6% 49%	943
October	Day	16% 7% 5% 5% 5% 6% 37%	907
	Night	19% 5% 5% 6% 38%	1126
November	Day	21% 7% 5% 7% 5% 6% 29%	1014
	Night	23% 9% 5% 7% 5% 6% 6% 25%	1519
December	Day	21% 8% 7% 5% 6% 8% 22%	928
	Night	20% 8% 5% 6% 6% 5% 6% 29%	1630

Percentage Cloud Cover
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month		Occurrence of each Forecast	Data Points
January	Day	17% 5% 6% 10% 6% 5% 6% 29%	751
	Night	19% 9% 5% 6% 5% 5% 6% 28%	1289
February	Day	15% 6% 6% 8% 10% 6% 5% 7% 26%	779
	Night	14% 8% 6% 6% 7% 8% 6% 5% 6% 24%	1001
March	Day	15% 8% 6% 6% 5% 5% 6% 35%	1005
	Night	17% 5% 6% 6% 5% 6% 34%	1036
April	Day	22% 6% 5% 6% 36%	1089
	Night	18% 6% 6% 6% 5% 5% 5% 35%	887
May	Day	19% 5% 5% 6% 5% 6% 7% 32%	1272
	Night	21% 5% 5% 5% 5% 7% 35%	775
June	Day	19% 5% 5% 7% 6% 7% 9% 26%	1260
	Night	16% 5% 5% 5% 6% 7% 7% 7% 32%	720
July	Day	11% 5% 5% 9% 6% 7% 10% 31%	1301
	Night	16% 5% 9% 6% 8% 8% 32%	741
August	Day	12% 6% 5% 6% 6% 5% 5% 8% 37%	1155
	Night	12% 5% 5% 6% 5% 7% 39%	874
September	Day	15% 5% 7% 44%	1032
	Night	16% 6% 48%	944
October	Day	16% 7% 5% 5% 5% 6% 38%	907
	Night	19% 5% 6% 5% 6% 38%	1126
November	Day	21% 7% 5% 7% 6% 5% 29%	1012
	Night	22% 9% 7% 5% 6% 6% 26%	1518
December	Day	21% 8% 5% 7% 5% 7% 8% 22%	928
	Night	20% 9% 5% 6% 5% 5% 5% 6% 29%	1634

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	13% 26% 25% 9%	474
	Night	12% 22% 28% 11%	771
February	Day	10% 23% 16% 12%	504
	Night	13% 20% 22% 9%	646
March	Day	5% 17% 29% 20%	663
	Night	9% 22% 29% 15%	705
April	Day	7% 17% 24% 20% 8%	709
	Night	7% 15% 26% 23% 5%	571
May	Day	9% 17% 30% 12%	838
	Night	7% 17% 25% 18%	540
June	Day	13% 33% 23% 6%	762
	Night	15% 29% 26% 10%	446
July	Day	11% 26% 25% 10%	678
	Night	12% 20% 30% 9%	421
August	Day	8% 14% 28% 16%	962
	Night	8% 13% 28% 17%	726
September	Day	7% 16% 26% 22%	853
	Night	6% 8% 36% 23%	787
October	Day	5% 12% 25% 17%	756
	Night	17% 21% 18%	931
November	Day	9% 16% 24% 9%	734
	Night	7% 18% 20% 8%	1080
December	Day	10% 23% 18% 6%	643
	Night	10% 22% 21% 6%	1210

Seeing (when cloud cover <= 80%)
Color Meanings: Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month		Occurrence of each Forecast	Data Points
January	Night	20% 48% 22%	319
February	Day	17% 39% 30%	46
	Night	22% 42% 22%	290
March	Day	25% 28% 27% 6%	87
	Night	29% 42% 16%	338
April	Day	15% 35% 17% 13% 8%	80
	Night	22% 39% 23% 6%	310
May	Day	15% 34% 21% 14%	85
	Night	20% 33% 28% 7%	199
June	Day	8% 21% 36% 27%	73
	Night	10% 26% 43% 16%	150
July	Day	8% 28% 31% 26%	80
	Night	9% 24% 44% 14%	154
August	Day	5% 15% 28% 24% 10%	85
	Night	26% 42% 15%	288
September	Day	8% 16% 26% 23% 12%	80
	Night	7% 28% 35% 13%	335
October	Day	12% 29% 22% 21%	87
	Night	13% 33% 29% 10%	350
November	Day	8% 38% 27% 7%	80
	Night	16% 36% 25% 5%	408
December	Night	22% 37% 21%	432

Page generated at 2008-12-24 22:45:28. Version ab11