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Potawatomi Wildlife Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Potawatomi Wildlife Park clear sky chart from 2005-11-05 to 2008-11-27.

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% 7% 5% 5% 5% 7% 32%	12266
	Night	20% 8% 5% 5% 7% 32%	12127
Cloud Cover	Day	17% 8% 5% 5% 5% 5% 5% 7% 32%	12284
	Night	20% 8% 5% 5% 5% 5% 7% 31%	12150
Transparency	Day	8% 17% 23% 16%	8208
	Night	8% 17% 23% 17%	8196
Seeing	Day	5% 25% 29% 22% 8%	730
	Night	11% 32% 30% 12%	3528

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	24% 19% 11% 5% 5% 16%	742
	Night	28% 17% 6% 5% 5% 20%	1299
February	Day	20% 14% 11% 7% 6% 5% 5% 6% 15%	802
	Night	21% 9% 10% 6% 5% 7% 24%	987
March	Day	27% 9% 6% 7% 5% 5% 7% 20%	975
	Night	25% 7% 5% 5% 5% 7% 25%	1025
April	Day	17% 7% 5% 5% 6% 36%	1109
	Night	20% 7% 6% 37%	868
May	Day	19% 6% 8% 36%	1231
	Night	19% 5% 5% 5% 8% 35%	814
June	Day	13% 8% 5% 6% 8% 38%	1250
	Night	11% 6% 5% 8% 48%	719
July	Day	9% 5% 6% 5% 7% 9% 43%	1300
	Night	7% 5% 6% 8% 48%	743
August	Day	10% 7% 5% 6% 6% 43%	1160
	Night	10% 5% 6% 10% 45%	876
September	Day	16% 5% 5% 7% 43%	1014
	Night	15% 6% 50%	960
October	Day	19% 6% 5% 7% 35%	918
	Night	21% 6% 5% 40%	1115
November	Day	23% 13% 6% 6% 26%	1002
	Night	22% 13% 6% 5% 7% 24%	1444
December	Day	24% 13% 8% 9% 6% 5% 5% 14%	763
	Night	28% 12% 7% 8% 7% 6% 5% 13%	1277

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% 19% 10% 6% 6% 15%	741
	Night	28% 16% 7% 5% 5% 5% 20%	1299
February	Day	20% 15% 11% 8% 5% 5% 5% 5% 15%	800
	Night	20% 9% 9% 5% 6% 5% 5% 6% 24%	978
March	Day	28% 9% 7% 7% 5% 8% 19%	996
	Night	26% 8% 6% 5% 5% 7% 24%	1049
April	Day	17% 6% 5% 5% 6% 37%	1108
	Night	19% 5% 6% 7% 36%	868
May	Day	18% 6% 5% 8% 35%	1230
	Night	18% 6% 5% 5% 6% 7% 34%	814
June	Day	13% 8% 6% 6% 8% 37%	1260
	Night	10% 5% 5% 5% 8% 47%	720
July	Day	8% 5% 7% 5% 7% 10% 41%	1300
	Night	6% 5% 6% 9% 47%	744
August	Day	10% 6% 6% 5% 5% 5% 6% 43%	1155
	Night	10% 5% 7% 11% 43%	877
September	Day	14% 6% 5% 6% 43%	1013
	Night	15% 6% 49%	961
October	Day	17% 7% 5% 5% 6% 7% 35%	918
	Night	19% 7% 5% 40%	1115
November	Day	22% 13% 6% 6% 7% 25%	1000
	Night	21% 13% 5% 6% 5% 6% 24%	1444
December	Day	23% 13% 9% 9% 6% 5% 14%	763
	Night	28% 11% 7% 9% 7% 5% 6% 13%	1281

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	11% 21% 16% 5%	371
	Night	8% 25% 18% 8%	702
February	Day	12% 20% 13%	471
	Night	11% 23% 16% 9%	639
March	Day	9% 26% 19% 5%	547
	Night	9% 21% 26% 6%	631
April	Day	8% 17% 27% 19%	748
	Night	9% 13% 26% 25%	593
May	Day	7% 20% 30% 17%	833
	Night	7% 15% 30% 21%	542
June	Day	7% 20% 31% 18%	891
	Night	7% 25% 29% 20%	535
July	Day	10% 17% 24% 24%	710
	Night	8% 17% 24% 25% 5%	414
August	Day	7% 13% 20% 23% 6%	953
	Night	7% 14% 22% 28% 5%	740
September	Day	12% 23% 24% 6%	815
	Night	5% 10% 28% 25% 8%	805
October	Day	7% 10% 25% 19%	759
	Night	9% 27% 22%	902
November	Day	6% 21% 18% 10%	696
	Night	6% 18% 18% 13%	1017
December	Day	13% 18% 15%	414
	Night	12% 16% 16%	676

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	23% 42% 19%	371
February	Night	12% 49% 19%	286
March	Day	12% 27% 27% 10% 5%	40
	Night	12% 38% 25% 9%	291
April	Day	7% 37% 34% 11%	79
	Night	10% 38% 29% 10%	241
May	Day	29% 31% 19% 8%	99
	Night	5% 32% 35% 16%	248
June	Day	6% 28% 26% 18% 8%	158
	Night	30% 43% 19%	236
July	Day	5% 26% 31% 23% 8%	146
	Night	18% 49% 25%	223
August	Day	11% 29% 36% 16%	86
	Night	11% 49% 25%	254
September	Day	16% 26% 35% 11%	80
	Night	6% 14% 32% 31%	295
October	Day	9% 21% 30% 16% 9%	42
	Night	14% 29% 28% 10%	337
November	Night	14% 33% 29%	385
December	Night	15% 40% 22%	361

Page generated at 2008-11-27 13:47:43. Version ab11