Beauclerc / San Jose(FL)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beauclerc / San Jose(FL) clear sky chart from 2005-11-05 to 2009-12-29.

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	11% 6% 6% 6% 6% 5% 6% 8% 34%	16500
	Night	10% 5% 5% 5% 5% 5% 6% 9% 41%	16462
Transparency	Day	8% 15% 19% 17% 6%	13145
	Night	7% 18% 21% 17% 7%	13476
Seeing	Day	5% 15% 20% 29% 19%	1021
	Night	8% 23% 31% 24%	5240

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	15% 7% 5% 6% 6% 38%	1100
	Night	15% 6% 6% 7% 39%	1598
February	Day	10% 5% 5% 6% 51%	1104
	Night	10% 5% 52%	1290
March	Day	7% 5% 6% 52%	1363
	Night	6% 7% 52%	1361
April	Day	9% 6% 9% 47%	1358
	Night	6% 5% 5% 5% 8% 51%	1247
May	Day	11% 5% 5% 5% 7% 6% 5% 9% 36%	1598
	Night	6% 5% 5% 5% 5% 6% 9% 46%	1100
June	Day	8% 5% 7% 9% 8% 9% 11% 28%	1552
	Night	8% 6% 6% 9% 15% 34%	1078
July	Day	11% 7% 5% 9% 9% 6% 10% 8% 8% 10% 12%	1595
	Night	7% 6% 6% 5% 8% 9% 9% 12% 25%	1097
August	Day	12% 7% 7% 6% 5% 7% 7% 9% 10% 20%	1510
	Night	8% 6% 7% 6% 7% 7% 7% 11% 30%	1199
September	Day	14% 8% 8% 8% 5% 8% 7% 6% 7% 21%	1303
	Night	11% 7% 5% 7% 7% 7% 7% 10% 28%	1301
October	Day	14% 9% 5% 7% 6% 6% 6% 7% 30%	1254
	Night	11% 5% 6% 6% 5% 8% 39%	1440
November	Day	9% 5% 5% 5% 5% 8% 44%	1394
	Night	10% 5% 5% 7% 48%	1773
December	Day	15% 5% 5% 5% 9% 35%	1369
	Night	14% 6% 6% 5% 5% 7% 39%	1978

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	5% 10% 17% 24% 11%	804
	Night	5% 15% 20% 19% 13%	1194
February	Day	11% 20% 25% 18%	890
	Night	12% 20% 23% 20%	1046
March	Day	14% 31% 25% 5%	1132
	Night	5% 18% 31% 20% 6%	1145
April	Day	5% 14% 21% 25% 13%	1115
	Night	7% 17% 22% 24% 10%	1042
May	Day	7% 15% 22% 21%	1254
	Night	8% 22% 24% 21%	924
June	Day	14% 29% 18% 11%	1146
	Night	13% 35% 25% 6%	830
July	Day	13% 22% 10%	959
	Night	19% 30% 12%	718
August	Day	14% 20% 15%	1319
	Night	13% 26% 20%	1053
September	Day	8% 13% 11% 9%	1130
	Night	10% 19% 15% 10%	1129
October	Day	6% 7% 14% 16% 7%	1114
	Night	7% 13% 15% 19% 7%	1313
November	Day	12% 22% 23% 10%	1186
	Night	13% 22% 23% 9%	1494
December	Day	5% 12% 25% 17% 5%	1096
	Night	5% 14% 22% 20% 6%	1588

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	17% 33% 25% 14%	448
February	Day	7% 28% 35% 28%	14
	Night	11% 35% 36% 9%	404
March	Day	6% 23% 28% 31% 5%	119
	Night	10% 31% 36% 15%	477
April	Day	13% 29% 22% 19% 9%	113
	Night	9% 39% 33% 11%	456
May	Day	21% 19% 26% 19%	119
	Night	23% 34% 26%	363
June	Day	20% 37% 28%	109
	Night	12% 34% 38% 8%	329
July	Day	5% 15% 34% 35%	105
	Night	27% 50% 10%	320
August	Day	5% 12% 31% 37%	116
	Night	22% 44% 17%	395
September	Day	9% 10% 35% 25%	113
	Night	12% 29% 36% 7%	449
October	Day	9% 11% 26% 29% 9%	119
	Night	6% 18% 34% 25%	481
November	Day	8% 27% 27% 22% 6%	94
	Night	12% 27% 32% 16%	554
December	Night	12% 31% 28% 17%	564

Page generated at 2009-12-30 05:20:38. Version ab11