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Lake Erie Metropark
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Erie Metropark 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	16% 8% 5% 6% 5% 5% 7% 32%	12207
	Night	19% 8% 5% 5% 5% 5% 6% 31%	12173
Cloud Cover	Day	15% 8% 6% 6% 5% 6% 5% 7% 31%	12227
	Night	19% 8% 5% 6% 5% 5% 6% 30%	12194
Transparency	Day	10% 18% 23% 14%	8191
	Night	9% 17% 22% 14%	8001
Seeing	Day	7% 24% 28% 24% 7%	738
	Night	10% 31% 31% 13%	3604

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% 14% 9% 7% 8% 5% 5% 13%	778
	Night	30% 13% 7% 5% 6% 5% 17%	1262
February	Day	23% 9% 9% 10% 7% 9% 14%	774
	Night	21% 10% 8% 9% 5% 6% 6% 20%	1017
March	Day	22% 14% 9% 7% 22%	977
	Night	21% 10% 6% 5% 6% 5% 6% 27%	1020
April	Day	16% 7% 5% 8% 38%	1119
	Night	18% 8% 5% 5% 5% 6% 34%	861
May	Day	16% 8% 5% 5% 6% 5% 6% 35%	1209
	Night	18% 7% 6% 5% 8% 33%	837
June	Day	9% 5% 6% 8% 5% 6% 11% 34%	1239
	Night	8% 5% 6% 5% 5% 9% 42%	719
July	Day	10% 5% 9% 45%	1268
	Night	7% 7% 5% 6% 8% 48%	774
August	Day	12% 5% 6% 6% 5% 6% 5% 6% 38%	1197
	Night	10% 5% 6% 6% 49%	838
September	Day	13% 5% 7% 45%	995
	Night	12% 6% 5% 5% 48%	979
October	Day	16% 7% 5% 7% 39%	923
	Night	15% 7% 5% 5% 6% 40%	1111
November	Day	22% 11% 6% 6% 5% 7% 24%	990
	Night	24% 10% 5% 5% 6% 26%	1455
December	Day	23% 14% 11% 8% 6% 6% 5% 13%	738
	Night	28% 11% 9% 8% 5% 5% 5% 14%	1300

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% 14% 8% 8% 9% 5% 5% 12%	777
	Night	30% 13% 7% 6% 5% 5% 16%	1262
February	Day	22% 9% 9% 9% 8% 5% 8% 5% 13%	772
	Night	19% 9% 8% 9% 6% 7% 6% 18%	1008
March	Day	21% 15% 8% 6% 6% 5% 22%	1000
	Night	22% 8% 6% 8% 5% 5% 25%	1042
April	Day	15% 5% 6% 5% 6% 7% 38%	1118
	Night	16% 9% 5% 5% 5% 7% 33%	861
May	Day	14% 8% 5% 6% 6% 6% 6% 34%	1208
	Night	18% 5% 5% 5% 5% 5% 9% 32%	837
June	Day	8% 5% 6% 6% 6% 7% 11% 34%	1249
	Night	8% 5% 6% 6% 5% 6% 9% 41%	720
July	Day	10% 6% 5% 9% 45%	1268
	Night	6% 6% 6% 9% 48%	775
August	Day	10% 6% 6% 6% 5% 6% 7% 37%	1192
	Night	9% 5% 5% 7% 47%	839
September	Day	12% 5% 5% 5% 45%	994
	Night	13% 5% 5% 5% 47%	980
October	Day	14% 6% 5% 5% 6% 8% 39%	923
	Night	15% 5% 5% 5% 6% 39%	1111
November	Day	20% 13% 6% 7% 5% 5% 5% 7% 22%	988
	Night	25% 9% 6% 6% 5% 6% 25%	1455
December	Day	23% 13% 12% 10% 5% 7% 12%	738
	Night	28% 12% 9% 8% 6% 5% 13%	1304

Transparency (when cloud cover <= 30%)
Color Meanings: Poor Below Average Average Above average Transparent
Month		Occurrence of each Forecast	Data Points
January	Day	13% 21% 11%	397
	Night	9% 19% 16% 5%	644
February	Day	16% 20% 11%	418
	Night	13% 19% 16% 5%	599
March	Day	11% 19% 21% 6%	532
	Night	8% 19% 24% 8%	615
April	Day	9% 20% 27% 21%	747
	Night	8% 17% 24% 22%	547
May	Day	10% 18% 28% 14%	834
	Night	9% 19% 25% 14%	575
June	Day	13% 24% 25% 14%	937
	Night	9% 21% 30% 18%	531
July	Day	10% 22% 28% 21%	710
	Night	11% 19% 25% 23%	445
August	Day	10% 14% 21% 19%	1000
	Night	9% 13% 24% 23%	715
September	Day	8% 15% 30% 20%	799
	Night	7% 11% 31% 20%	788
October	Day	6% 15% 26% 18%	753
	Night	6% 14% 25% 20%	908
November	Day	10% 16% 17% 10%	690
	Night	8% 18% 18% 10%	1001
December	Day	16% 19% 9%	374
	Night	15% 18% 12%	633

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	19% 41% 23%	346
February	Night	9% 50% 24%	283
March	Day	11% 29% 32% 12%	62
	Night	13% 38% 26% 8%	333
April	Day	9% 32% 29% 15%	82
	Night	10% 37% 32% 10%	265
May	Day	34% 19% 25% 9%	83
	Night	5% 28% 33% 17%	253
June	Day	20% 40% 24% 5%	159
	Night	16% 49% 24%	237
July	Day	6% 15% 33% 29% 9%	115
	Night	14% 47% 27%	233
August	Day	16% 25% 33% 10%	86
	Night	18% 40% 29%	254
September	Day	10% 20% 15% 34% 11%	84
	Night	7% 17% 31% 28% 7%	325
October	Day	10% 34% 23% 14% 5%	67
	Night	11% 29% 34% 11%	344
November	Night	14% 32% 24% 9%	393
December	Night	16% 36% 26% 5%	338

Page generated at 2008-11-27 13:47:51. Version ab11