TheDamObservatory-Lake Tschida
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the TheDamObservatory-Lake Tschida clear sky chart from 2005-11-06 to 2024-03-06.

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	9% 7% 3 6% 6% 3 5% 5% 6% 8% 43%	78210
	Night	7% 7% 3 6% 6% 3 5% 5% 6% 8% 43%	81346
Transparency	Day	39% 5% 14% 27% 13% 2	77913
	Night	39% 5% 14% 26% 13% 2	81165
Seeing	Day	13% 9% 30% 30% 15% 3	15038
	Night	11% 8% 33% 35% 11% 1	25220

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	3 8% 5% 10% 10% 4 6% 5% 6% 8% 36%	2538
	11th to 20th	Day	3 6% 4 10% 8% 4 8% 9% 10% 11% 26%	2540
	21st to end	Day	3 10% 6% 10% 7% 4 6% 5% 5% 7% 37%	2794
February	1st to 10th	Day	8% 11% 6% 9% 8% 4 5% 4 5% 6% 34%	1542
	11th to 20th	Day	5% 11% 5% 10% 7% 3 5% 6% 6% 6% 33%	1827
	21st to end	Day	5% 11% 6% 10% 9% 3 5% 5% 5% 7% 34%	1570
March	1st to 10th	Day	9% 11% 5% 10% 7% 4 5% 4 5% 7% 33%	1850
	11th to 20th	Day	9% 8% 3 7% 6% 3 5% 5% 5% 7% 41%	1868
	21st to end	Day	14% 11% 4 7% 7% 3 5% 5% 5% 7% 31%	2322
April	1st to 10th	Day	10% 9% 4 7% 5% 4 5% 5% 7% 8% 37%	2160
	11th to 20th	Day	15% 11% 5% 8% 6% 3 5% 4 6% 6% 32%	2193
	21st to end	Day	16% 9% 3 6% 5% 3 5% 5% 5% 7% 37%	2340
May	1st to 10th	Day	13% 9% 2 6% 5% 2 4 5% 5% 7% 41%	2398
	11th to 20th	Day	14% 6% 2 5% 5% 3 4 5% 6% 8% 42%	2478
	21st to end	Day	15% 8% 3 6% 5% 3 5% 5% 5% 8% 36%	2724
June	1st to 10th	Day	13% 5% 2 4 5% 3 4 5% 6% 8% 46%	2628
	11th to 20th	Day	10% 5% 2 4 6% 3 5% 4 6% 9% 45%	2700
	21st to end	Day	7% 4 2 4 4 2 4 5% 5% 9% 54%	2630
July	1st to 10th	Day	6% 3 1 4 4 3 5% 5% 6% 9% 53%	2520
	11th to 20th	Day	4 3 2 3 4 3 4 3 5% 8% 61%	2520
	21st to end	Day	5% 2 1 3 4 3 4 5% 5% 8% 58%	2742
August	1st to 10th	Day	7% 4 2 5% 4 3 4 5% 6% 8% 51%	2507
	11th to 20th	Day	9% 4 2 3 4 3 4 4 5% 8% 55%	2326
	21st to end	Day	6% 4 2 4 4 3 3 3 4 7% 60%	2430
September	1st to 10th	Day	9% 4 2 3 4 3 4 3 5% 5% 57%	2160
	11th to 20th	Day	10% 5% 1 3 4 2 3 4 5% 7% 55%	2035
	21st to end	Day	12% 5% 2 4 4 3 2 3 4 7% 54%	1980
October	1st to 10th	Day	14% 6% 2 5% 5% 3 3 3 5% 7% 47%	1949
	11th to 20th	Day	12% 9% 3 6% 5% 2 4 4 5% 7% 44%	1670
	21st to end	Day	10% 9% 4 5% 5% 3 4 4 5% 8% 43%	1782
November	1st to 10th	Day	10% 10% 4 5% 5% 3 5% 4 6% 7% 42%	1673
	11th to 20th	Day	6% 7% 4 7% 8% 3 4 5% 6% 8% 40%	1691
	21st to end	Day	6% 8% 4 8% 7% 4 5% 5% 6% 8% 39%	1440
December	1st to 10th	Day	6% 10% 4 8% 7% 4 5% 5% 6% 8% 36%	1330
	11th to 20th	Day	5% 11% 5% 9% 6% 3 6% 5% 6% 9% 36%	1683
	21st to end	Day	8% 9% 4 7% 7% 4 5% 3 4 7% 41%	2670
January	1st to 10th	Night	4 9% 5% 9% 10% 4 6% 5% 5% 6% 37%	4417
	11th to 20th	Night	3 8% 4 8% 7% 6% 11% 10% 8% 9% 27%	4430
	21st to end	Night	3 9% 5% 9% 6% 4 6% 6% 6% 8% 38%	4873
February	1st to 10th	Night	8% 10% 5% 8% 8% 5% 6% 6% 6% 8% 31%	2656
	11th to 20th	Night	5% 8% 4 10% 8% 4 4 5% 6% 7% 39%	2238
	21st to end	Night	6% 9% 5% 8% 6% 4 5% 4 5% 7% 41%	1884
March	1st to 10th	Night	7% 9% 5% 8% 8% 5% 7% 5% 5% 6% 36%	2226
	11th to 20th	Night	10% 8% 4 5% 6% 3 4 5% 5% 7% 42%	2091
	21st to end	Night	11% 10% 4 7% 7% 3 5% 5% 7% 7% 34%	2030
April	1st to 10th	Night	7% 8% 3 7% 5% 3 7% 7% 8% 8% 39%	1800
	11th to 20th	Night	12% 9% 5% 7% 7% 3 5% 5% 6% 7% 34%	1714
	21st to end	Night	13% 5% 3 5% 5% 3 5% 5% 5% 8% 42%	1620
May	1st to 10th	Night	10% 5% 2 4 6% 4 6% 5% 5% 9% 44%	1558
	11th to 20th	Night	11% 6% 2 6% 6% 3 5% 6% 6% 8% 44%	1417
	21st to end	Night	14% 5% 2 4 4 2 5% 5% 7% 9% 43%	1552
June	1st to 10th	Night	9% 3 2 3 4 2 4 5% 8% 10% 49%	1327
	11th to 20th	Night	10% 4 2 6% 5% 3 5% 5% 6% 8% 46%	1260
	21st to end	Night	4 3 1 3 3 2 4 4 7% 9% 58%	1323
July	1st to 10th	Night	5% 3 2 4 4 2 4 4 7% 11% 56%	1440
	11th to 20th	Night	3 4 1 3 4 2 3 5% 5% 7% 63%	1440
	21st to end	Night	5% 2 1 3 3 2 3 4 5% 9% 65%	1576
August	1st to 10th	Night	4 3 1 3 4 3 4 4 5% 8% 59%	1432
	11th to 20th	Night	7% 4 1 3 4 3 3 5% 5% 7% 59%	1575
	21st to end	Night	5% 3 1 2 4 2 3 4 5% 8% 63%	1924
September	1st to 10th	Night	7% 3 2 3 3 1 3 4 5% 7% 63%	1800
	11th to 20th	Night	9% 5% 2 4 4 2 3 4 5% 8% 55%	1924
	21st to end	Night	13% 5% 2 4 3 2 3 4 4 7% 54%	1980
October	1st to 10th	Night	15% 6% 2 5% 4 3 3 4 5% 7% 45%	2007
	11th to 20th	Night	10% 8% 3 4 4 3 4 6% 5% 7% 46%	2272
	21st to end	Night	10% 8% 3 6% 6% 2 4 4 5% 8% 45%	2574
November	1st to 10th	Night	7% 8% 4 6% 5% 2 4 5% 6% 8% 43%	2405
	11th to 20th	Night	6% 7% 4 7% 8% 4 5% 5% 5% 8% 41%	2487
	21st to end	Night	7% 7% 3 7% 6% 3 5% 5% 6% 8% 44%	2738
December	1st to 10th	Night	7% 10% 4 9% 7% 4 5% 5% 5% 7% 35%	2850
	11th to 20th	Night	6% 8% 4 7% 7% 4 5% 5% 6% 8% 40%	3514
	21st to end	Night	10% 11% 4 7% 7% 4 5% 5% 4 6% 38%	4992

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	46% 5% 19% 23% 6%	2539
	11th to 20th	Day	49% 5% 14% 17% 14% 1	2540
	21st to end	Day	47% 5% 14% 27% 6%	2794
February	1st to 10th	Day	53% 4 13% 20% 10% 1	1542
	11th to 20th	Day	50% 4 12% 23% 9% 1	1837
	21st to end	Day	49% 5% 13% 22% 10% 1	1570
March	1st to 10th	Day	52% 5% 15% 18% 8%	1850
	11th to 20th	Day	42% 4 15% 26% 12% 1	1868
	21st to end	Day	52% 5% 17% 21% 5% 1	2322
April	1st to 10th	Day	44% 5% 16% 22% 12% 2	2160
	11th to 20th	Day	52% 5% 12% 21% 10% 1	2196
	21st to end	Day	47% 5% 13% 24% 9% 1	2340
May	1st to 10th	Day	42% 4 12% 29% 12% 1	2398
	11th to 20th	Day	39% 5% 14% 27% 14%	2482
	21st to end	Day	46% 6% 16% 25% 8%	2724
June	1st to 10th	Day	36% 5% 17% 30% 11% 1	2628
	11th to 20th	Day	36% 6% 17% 28% 11% 2	2700
	21st to end	Day	27% 6% 20% 31% 15% 1	2630
July	1st to 10th	Day	25% 6% 16% 35% 15% 4	2451
	11th to 20th	Day	22% 5% 14% 31% 22% 7%	2445
	21st to end	Day	23% 5% 13% 32% 22% 4	2590
August	1st to 10th	Day	30% 5% 14% 29% 17% 5%	2491
	11th to 20th	Day	29% 4 13% 33% 19% 2	2326
	21st to end	Day	25% 4 13% 30% 24% 4	2430
September	1st to 10th	Day	29% 3 11% 33% 19% 4	2160
	11th to 20th	Day	30% 4 14% 32% 18% 2	2035
	21st to end	Day	32% 3 11% 33% 19% 2	1980
October	1st to 10th	Day	39% 4 15% 27% 14% 1	1949
	11th to 20th	Day	40% 4 11% 29% 14% 2	1670
	21st to end	Day	40% 6% 15% 24% 14% 2	1782
November	1st to 10th	Day	41% 6% 14% 23% 15% 2	1673
	11th to 20th	Day	41% 5% 16% 26% 10% 2	1691
	21st to end	Day	42% 6% 18% 23% 11% 1	1440
December	1st to 10th	Day	47% 5% 14% 25% 9% 1	1330
	11th to 20th	Day	45% 5% 19% 24% 7%	1680
	21st to end	Day	45% 4 10% 29% 12% 1	2670
January	1st to 10th	Night	48% 4 16% 23% 9% 1	4417
	11th to 20th	Night	49% 6% 15% 20% 8% 1	4430
	21st to end	Night	44% 6% 16% 26% 7%	4873
February	1st to 10th	Night	50% 5% 13% 19% 12%	2656
	11th to 20th	Night	44% 5% 13% 26% 11% 2	2238
	21st to end	Night	44% 3 13% 24% 13% 2	1884
March	1st to 10th	Night	49% 5% 14% 21% 10%	2226
	11th to 20th	Night	41% 5% 11% 28% 13% 1	2091
	21st to end	Night	48% 6% 18% 20% 8% 1	2030
April	1st to 10th	Night	40% 6% 13% 25% 14% 2	1800
	11th to 20th	Night	47% 5% 10% 22% 13% 2	1714
	21st to end	Night	40% 6% 13% 25% 14% 1	1620
May	1st to 10th	Night	36% 5% 14% 28% 15% 1	1558
	11th to 20th	Night	36% 6% 17% 24% 16% 1	1418
	21st to end	Night	36% 7% 21% 26% 9% 1	1552
June	1st to 10th	Night	29% 6% 18% 33% 13% 2	1327
	11th to 20th	Night	35% 8% 18% 26% 12% 2	1260
	21st to end	Night	22% 5% 20% 34% 17% 2	1323
July	1st to 10th	Night	23% 4 17% 36% 15% 5%	1400
	11th to 20th	Night	21% 5% 14% 32% 21% 7%	1392
	21st to end	Night	18% 4 13% 34% 25% 5%	1488
August	1st to 10th	Night	23% 5% 15% 31% 20% 6%	1424
	11th to 20th	Night	26% 4 13% 33% 20% 4	1575
	21st to end	Night	21% 5% 11% 33% 25% 5%	1924
September	1st to 10th	Night	22% 4 10% 35% 24% 5%	1800
	11th to 20th	Night	28% 4 14% 31% 20% 2	1924
	21st to end	Night	31% 4 11% 33% 19% 1	1980
October	1st to 10th	Night	38% 5% 13% 26% 17% 1	2007
	11th to 20th	Night	37% 4 10% 31% 16% 2	2272
	21st to end	Night	38% 4 14% 26% 15% 2	2574
November	1st to 10th	Night	39% 5% 12% 24% 18% 2	2405
	11th to 20th	Night	42% 5% 14% 25% 12% 2	2487
	21st to end	Night	38% 6% 18% 27% 11% 1	2738
December	1st to 10th	Night	48% 5% 15% 22% 8% 1	2850
	11th to 20th	Night	42% 5% 21% 24% 8%	3516
	21st to end	Night	48% 3 10% 24% 13% 1	4992

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	9% 11% 34% 30% 11% 5%	270
	11th to 20th	Day	10% 13% 39% 26% 7% 5%	270
	21st to end	Day	8% 13% 39% 23% 15% 2	297
February	1st to 10th	Day	10% 13% 41% 30% 6%	270
	11th to 20th	Day	13% 9% 44% 26% 7% 1	270
	21st to end	Day	13% 10% 35% 33% 8%	225
March	1st to 10th	Day	18% 11% 36% 25% 7% 2	255
	11th to 20th	Day	11% 10% 38% 28% 11% 2	240
	21st to end	Day	15% 10% 31% 29% 11% 4	408
April	1st to 10th	Day	15% 16% 35% 25% 8%	420
	11th to 20th	Day	20% 14% 35% 25% 5% 1	474
	21st to end	Day	21% 10% 27% 25% 15% 2	600
May	1st to 10th	Day	15% 9% 29% 31% 14% 3	603
	11th to 20th	Day	16% 8% 27% 31% 14% 3	625
	21st to end	Day	16% 9% 27% 25% 18% 5%	679
June	1st to 10th	Day	13% 8% 23% 29% 22% 5%	630
	11th to 20th	Day	13% 7% 35% 29% 13% 3	630
	21st to end	Day	10% 9% 25% 35% 19% 3	630
July	1st to 10th	Day	6% 6% 26% 39% 20% 3	621
	11th to 20th	Day	6% 6% 28% 40% 18% 2	618
	21st to end	Day	5% 4 26% 42% 21% 2	684
August	1st to 10th	Day	8% 4 24% 37% 23% 5%	626
	11th to 20th	Day	9% 3 22% 35% 24% 6%	615
	21st to end	Day	9% 5% 21% 35% 23% 5%	549
September	1st to 10th	Day	11% 9% 30% 29% 17% 4	450
	11th to 20th	Day	12% 4 28% 33% 19% 4	325
	21st to end	Day	19% 9% 31% 26% 14% 2	270
October	1st to 10th	Day	21% 8% 24% 26% 17% 4	270
	11th to 20th	Day	14% 16% 36% 19% 14% 1	270
	21st to end	Day	18% 15% 37% 24% 4 1	297
November	1st to 10th	Day	21% 9% 33% 21% 13% 3	270
	11th to 20th	Day	12% 14% 35% 26% 11% 2	270
	21st to end	Day	10% 16% 30% 33% 10% 1	270
December	1st to 10th	Day	12% 11% 39% 26% 10% 1	270
	11th to 20th	Day	13% 11% 44% 27% 4 1	270
	21st to end	Day	11% 12% 41% 24% 10% 3	297
January	1st to 10th	Night	9% 11% 39% 30% 10% 1	950
	11th to 20th	Night	11% 15% 36% 29% 9% 1	950
	21st to end	Night	9% 13% 37% 32% 8%	1045
February	1st to 10th	Night	12% 11% 36% 32% 8% 1	946
	11th to 20th	Night	8% 9% 42% 31% 9% 1	744
	21st to end	Night	11% 6% 34% 37% 11% 1	628
March	1st to 10th	Night	12% 12% 36% 31% 8% 1	742
	11th to 20th	Night	15% 6% 36% 30% 11% 2	651
	21st to end	Night	17% 6% 33% 31% 12% 1	594
April	1st to 10th	Night	10% 10% 39% 34% 8%	540
	11th to 20th	Night	16% 8% 41% 25% 10% 1	533
	21st to end	Night	15% 9% 28% 34% 13% 1	540
May	1st to 10th	Night	13% 6% 27% 39% 14%	540
	11th to 20th	Night	14% 5% 29% 41% 11% 1	531
	21st to end	Night	17% 5% 31% 34% 13% 1	584
June	1st to 10th	Night	11% 6% 27% 40% 16%	540
	11th to 20th	Night	13% 7% 33% 35% 12%	540
	21st to end	Night	6% 5% 28% 47% 14%	540
July	1st to 10th	Night	6% 2 27% 47% 17%	525
	11th to 20th	Night	6% 3 29% 50% 13%	522
	21st to end	Night	5% 3 23% 53% 16%	591
August	1st to 10th	Night	6% 2 25% 53% 14% 1	537
	11th to 20th	Night	8% 2 26% 45% 17% 2	534
	21st to end	Night	6% 3 28% 44% 18% 1	594
September	1st to 10th	Night	9% 4 25% 44% 16% 1	540
	11th to 20th	Night	10% 4 29% 42% 14% 1	540
	21st to end	Night	15% 6% 32% 36% 11% 1	540
October	1st to 10th	Night	19% 8% 25% 38% 10% 1	567
	11th to 20th	Night	15% 10% 28% 34% 12% 1	832
	21st to end	Night	14% 12% 36% 29% 9% 1	990
November	1st to 10th	Night	12% 11% 38% 31% 8%	925
	11th to 20th	Night	10% 11% 39% 29% 11%	950
	21st to end	Night	10% 12% 37% 33% 7%	950
December	1st to 10th	Night	13% 10% 36% 32% 9% 1	950
	11th to 20th	Night	12% 12% 35% 33% 8% 1	950
	21st to end	Night	16% 11% 33% 29% 10%	1045

Page generated at 2024-03-03 04:29:00. Version ac07

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