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Lake Hudson State Recreational Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Hudson State Recreational Area 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	19% 6% 6% 5% 6% 5% 7% 30%	8744
	Night	21% 6% 6% 5% 6% 7% 30%	8430
Transparency	Day	23% 18% 38% 18%	3952
	Night	22% 18% 40% 17%	4035
Seeing	Day	10% 24% 26% 25% 12%	577
	Night	13% 31% 33% 20%	2519

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	30% 9% 9% 6% 7% 6% 6% 11%	504
	Night	31% 9% 9% 6% 7% 15%	849
February	Day	24% 11% 8% 6% 6% 8% 20%	551
	Night	22% 10% 7% 6% 7% 5% 7% 21%	703
March	Day	31% 12% 11% 7% 5% 13%	663
	Night	23% 11% 6% 6% 5% 8% 6% 8% 18%	700
April	Day	20% 6% 6% 5% 7% 5% 5% 32%	750
	Night	22% 6% 7% 36%	572
May	Day	17% 7% 5% 5% 6% 5% 6% 6% 30%	804
	Night	18% 5% 6% 6% 5% 5% 36%	549
June	Day	14% 5% 5% 6% 7% 6% 9% 34%	840
	Night	12% 5% 8% 6% 9% 41%	476
July	Day	13% 5% 5% 7% 7% 11% 32%	852
	Night	19% 6% 6% 6% 10% 34%	510
August	Day	13% 5% 6% 5% 8% 5% 7% 34%	1192
	Night	11% 5% 9% 7% 8% 37%	850
September	Day	10% 5% 5% 7% 49%	985
	Night	11% 5% 5% 8% 50%	957
October	Day	18% 6% 5% 5% 7% 5% 5% 7% 31%	617
	Night	19% 5% 5% 6% 8% 8% 33%	745
November	Day	34% 7% 6% 6% 5% 23%	473
	Night	34% 7% 7% 5% 5% 22%	694
December	Day	32% 10% 7% 5% 5% 20%	513
	Night	30% 7% 7% 5% 5% 6% 20%	825

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	40% 21% 37%	96
	Night	29% 21% 41% 7%	209
February	Day	38% 22% 30% 9%	142
	Night	32% 21% 36% 7%	255
March	Day	43% 21% 27% 7%	144
	Night	31% 22% 39% 5%	244
April	Day	23% 14% 41% 18%	335
	Night	19% 10% 43% 24%	296
May	Day	27% 24% 39% 8%	351
	Night	24% 19% 49% 7%	267
June	Day	24% 11% 48% 13%	436
	Night	22% 14% 45% 17%	269
July	Day	20% 16% 38% 17% 6%	419
	Night	12% 12% 51% 19%	249
August	Day	21% 23% 37% 17%	566
	Night	20% 21% 38% 17%	468
September	Day	14% 15% 34% 33%	666
	Night	14% 14% 31% 36%	670
October	Day	20% 12% 44% 21%	452
	Night	22% 16% 43% 15%	558
November	Day	25% 27% 31% 14%	194
	Night	23% 26% 39% 10%	286
December	Day	30% 23% 24% 21%	151
	Night	30% 21% 38% 9%	264

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% 50% 21% 7%	204
February	Night	12% 40% 37% 9%	180
March	Day	20% 40% 31% 8%	35
	Night	20% 43% 32%	201
April	Day	18% 28% 34% 16%	49
	Night	18% 34% 35% 11%	151
May	Day	5% 35% 24% 28% 5%	53
	Night	11% 33% 38% 16%	168
June	Day	11% 26% 28% 22% 10%	109
	Night	5% 25% 42% 26%	168
July	Day	10% 23% 32% 22% 11%	103
	Night	7% 17% 44% 28%	157
August	Day	16% 21% 29% 27%	87
	Night	15% 35% 39% 6%	265
September	Day	11% 12% 17% 38% 18%	85
	Night	13% 33% 42% 5%	307
October	Day	5% 30% 28% 28% 7%	56
	Night	12% 30% 29% 27%	323
November	Night	21% 43% 28% 5%	188
December	Night	25% 45% 23%	207

Page generated at 2008-06-05 23:07:43. Version ab11