Conkles Hollow
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Conkles Hollow clear sky chart from 2005-11-05 to 2008-11-10.

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	18% 8% 5% 5% 5% 5% 7% 32%	12090
	Night	19% 7% 5% 7% 34%	11945
Cloud Cover	Day	19% 8% 5% 5% 5% 5% 6% 32%	12109
	Night	19% 7% 5% 7% 34%	11968
Transparency	Day	8% 16% 25% 15%	8114
	Night	8% 17% 24% 17%	8063
Seeing	Day	9% 24% 25% 19% 11%	637
	Night	16% 29% 28% 14%	3485

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	25% 15% 8% 6% 5% 19%	833
	Night	25% 12% 7% 6% 6% 22%	1207
February	Day	22% 13% 7% 7% 5% 6% 23%	777
	Night	24% 11% 6% 6% 5% 5% 26%	1013
March	Day	29% 12% 5% 27%	985
	Night	23% 9% 7% 7% 5% 7% 27%	1012
April	Day	18% 7% 5% 6% 40%	1103
	Night	18% 6% 5% 6% 5% 5% 6% 36%	875
May	Day	17% 6% 5% 5% 5% 7% 35%	1209
	Night	17% 6% 6% 8% 38%	837
June	Day	15% 6% 5% 6% 8% 35%	1161
	Night	11% 5% 7% 5% 10% 40%	808
July	Day	13% 5% 5% 5% 8% 5% 6% 7% 32%	1209
	Night	10% 5% 5% 6% 11% 42%	833
August	Day	10% 5% 5% 6% 5% 8% 11% 36%	1194
	Night	11% 5% 5% 5% 6% 8% 45%	840
September	Day	19% 5% 5% 6% 5% 41%	988
	Night	15% 5% 5% 5% 49%	988
October	Day	17% 7% 8% 41%	939
	Night	19% 5% 6% 44%	1094
November	Day	17% 11% 6% 5% 6% 5% 6% 29%	855
	Night	21% 8% 5% 5% 5% 5% 7% 30%	1234
December	Day	22% 13% 7% 7% 5% 6% 20%	837
	Night	24% 12% 8% 6% 6% 5% 6% 18%	1204

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	25% 14% 9% 6% 5% 19%	832
	Night	25% 12% 7% 6% 7% 22%	1208
February	Day	22% 14% 7% 8% 5% 25%	775
	Night	23% 12% 6% 6% 5% 27%	1004
March	Day	31% 11% 5% 5% 26%	1008
	Night	24% 8% 8% 6% 7% 27%	1034
April	Day	19% 6% 5% 6% 40%	1102
	Night	18% 6% 5% 5% 6% 6% 5% 36%	875
May	Day	17% 7% 5% 5% 7% 36%	1208
	Night	17% 7% 6% 8% 37%	837
June	Day	16% 7% 6% 8% 35%	1170
	Night	11% 5% 6% 5% 10% 40%	810
July	Day	14% 5% 5% 5% 8% 6% 6% 7% 32%	1209
	Night	10% 5% 7% 11% 42%	834
August	Day	10% 5% 5% 5% 6% 7% 12% 36%	1189
	Night	11% 5% 5% 5% 8% 45%	841
September	Day	19% 5% 5% 6% 5% 42%	987
	Night	15% 5% 49%	989
October	Day	17% 7% 7% 42%	939
	Night	19% 5% 5% 6% 44%	1094
November	Day	17% 10% 6% 5% 5% 5% 5% 5% 29%	853
	Night	21% 9% 5% 6% 31%	1234
December	Day	23% 13% 8% 7% 6% 20%	837
	Night	24% 11% 8% 6% 5% 5% 7% 18%	1208

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	9% 20% 21% 8%	420
	Night	8% 21% 24% 5%	652
February	Day	7% 21% 19% 6%	486
	Night	7% 23% 20% 6%	634
March	Day	6% 21% 24% 8%	566
	Night	7% 21% 27% 10%	621
April	Day	7% 19% 25% 15% 8%	779
	Night	7% 16% 24% 21% 7%	580
May	Day	11% 14% 27% 19%	835
	Night	10% 16% 24% 19% 5%	601
June	Day	10% 20% 28% 17%	789
	Night	10% 20% 34% 19%	554
July	Day	9% 16% 27% 15%	620
	Night	9% 16% 30% 20% 6%	469
August	Day	10% 15% 29% 14%	984
	Night	6% 14% 27% 22%	707
September	Day	8% 8% 20% 30%	789
	Night	5% 11% 18% 34% 6%	809
October	Day	5% 14% 26% 21%	792
	Night	6% 10% 27% 21% 5%	915
November	Day	10% 15% 24% 11%	557
	Night	8% 20% 21% 13% 5%	831
December	Day	9% 21% 20% 6%	497
	Night	11% 23% 18%	690

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	34% 35% 16%	300
February	Night	23% 38% 22%	284
March	Day	19% 37% 16% 13%	67
	Night	24% 35% 21% 5%	325
April	Day	10% 35% 30% 14%	78
	Night	20% 40% 21% 8%	272
May	Day	10% 27% 21% 19% 10%	87
	Night	12% 34% 25% 17%	263
June	Day	10% 27% 32% 15% 13%	80
	Night	5% 30% 43% 18%	238
July	Day	7% 13% 23% 19% 28%	76
	Night	21% 36% 30%	234
August	Day	20% 23% 30% 17%	86
	Night	18% 38% 31%	256
September	Day	8% 13% 19% 29% 17%	82
	Night	6% 16% 33% 31%	324
October	Day	12% 24% 33% 13%	81
	Night	12% 27% 30% 13%	337
November	Night	20% 24% 28% 13%	334
December	Night	23% 33% 24%	318

Page generated at 2008-11-11 07:54:52. Version ab11