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 2003-08-01 to 2005-11-07.

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	21% 5% 5% 6% 5% 5% 6% 30%	8736
	Night	24% 5% 5% 6% 6% 31%	8434
Transparency	Day	25% 18% 35% 19%	4083
	Night	22% 18% 37% 19%	4003
Seeing	Day	17% 27% 29% 19% 6%	559
	Night	22% 34% 28% 13%	2339

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	23% 7% 6% 6% 5% 5% 31%	497
	Night	25% 6% 6% 5% 8% 30%	855
February	Day	14% 5% 5% 6% 6% 5% 5% 39%	549
	Night	18% 5% 6% 5% 7% 36%	705
March	Day	27% 8% 5% 5% 6% 26%	672
	Night	26% 5% 5% 5% 5% 7% 27%	692
April	Day	23% 5% 5% 6% 39%	728
	Night	31% 5% 33%	592
May	Day	19% 5% 5% 5% 7% 6% 7% 30%	845
	Night	24% 6% 6% 6% 5% 7% 5% 25%	510
June	Day	15% 5% 5% 9% 6% 5% 8% 31%	840
	Night	17% 6% 5% 6% 6% 36%	476
July	Day	19% 5% 7% 6% 6% 8% 7% 5% 7% 23%	866
	Night	19% 6% 10% 5% 6% 5% 30%	496
August	Day	23% 5% 5% 5% 5% 7% 5% 7% 24%	1166
	Night	22% 5% 5% 5% 6% 5% 5% 7% 29%	871
September	Day	21% 7% 39%	1017
	Night	21% 5% 5% 44%	928
October	Day	27% 6% 32%	607
	Night	33% 6% 6% 6% 28%	754
November	Day	19% 5% 5% 9% 6% 7% 31%	463
	Night	25% 5% 9% 32%	703
December	Day	27% 8% 5% 5% 7% 6% 5% 5% 20%	486
	Night	26% 8% 7% 7% 26%	852

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	30% 19% 28% 17%	221
	Night	23% 18% 43% 14%	338
February	Day	29% 7% 38% 23%	284
	Night	23% 12% 38% 18% 6%	351
March	Day	29% 25% 34% 9%	271
	Night	23% 20% 39% 14%	281
April	Day	16% 9% 30% 38% 5%	376
	Night	21% 7% 31% 35%	254
May	Day	31% 19% 37% 11%	370
	Night	25% 16% 38% 19%	203
June	Day	23% 19% 41% 14%	392
	Night	18% 12% 39% 29%	225
July	Day	25% 16% 39% 17%	320
	Night	28% 13% 37% 17%	213
August	Day	27% 27% 32% 12%	464
	Night	23% 26% 29% 19%	369
September	Day	13% 13% 37% 34%	556
	Night	13% 17% 45% 22%	509
October	Day	23% 20% 41% 15%	389
	Night	22% 19% 41% 16%	510
November	Day	30% 24% 28% 15%	260
	Night	23% 32% 29% 14%	389
December	Day	36% 20% 33% 7%	180
	Night	28% 20% 36% 12%	361

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	41% 39% 17%	200
February	Day	15% 46% 34%	32
	Night	25% 45% 19% 8%	191
March	Day	19% 36% 28% 15%	46
	Night	28% 40% 26%	194
April	Day	16% 45% 20% 8% 8%	48
	Night	27% 36% 19% 16%	166
May	Day	18% 30% 37% 11%	53
	Night	19% 41% 26% 12%	124
June	Day	13% 41% 20% 24%	58
	Night	12% 32% 44% 11%	106
July	Day	17% 17% 32% 26% 5%	56
	Night	14% 24% 40% 20%	109
August	Day	19% 13% 28% 28% 9%	76
	Night	13% 27% 35% 22%	269
September	Day	15% 14% 25% 26% 18%	76
	Night	14% 20% 41% 22%	302
October	Day	16% 26% 30% 20% 5%	72
	Night	21% 30% 25% 20%	285
November	Day	23% 21% 38% 14%	42
	Night	20% 40% 27% 10%	197
December	Night	31% 43% 21%	196

Page generated at 2008-08-27 07:51:51. Version ab11