Michowka Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Michowka Observatory clear sky chart from 2005-11-06 to 2024-11-10.

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	14% 9% 3 7% 5% 4 4 4 5% 7% 38%	101622
	Night	13% 10% 4 8% 5% 4 4 3 5% 6% 38%	97619
Transparency	Day	44% 6% 12% 25% 12% 1	105140
	Night	45% 6% 12% 23% 13% 1	102241
Seeing	Day	17% 12% 29% 25% 13% 4	15996
	Night	17% 10% 31% 30% 10% 1	25849

By Month

Percentage Cloud Cover SE (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	10% 17% 9% 15% 5% 4 4 3 4 5% 24%	2527
	11th to 20th	Day	9% 13% 5% 13% 6% 6% 9% 8% 6% 5% 19%	2530
	21st to end	Day	15% 19% 7% 13% 5% 4 4 3 4 5% 22%	2912
February	1st to 10th	Day	9% 13% 5% 10% 5% 5% 5% 4 5% 8% 31%	1710
	11th to 20th	Day	11% 10% 4 7% 6% 5% 5% 4 5% 6% 35%	1722
	21st to end	Day	12% 12% 4 10% 6% 6% 4 4 5% 7% 31%	1570
March	1st to 10th	Day	13% 9% 3 5% 4 3 2 2 4 6% 49%	3120
	11th to 20th	Day	9% 8% 3 9% 4 5% 4 4 5% 6% 43%	3434
	21st to end	Day	21% 12% 4 10% 5% 4 4 3 5% 6% 28%	4065
April	1st to 10th	Day	17% 12% 4 8% 5% 5% 5% 3 5% 5% 31%	2280
	11th to 20th	Day	21% 10% 3 8% 5% 4 3 3 4 5% 34%	2254
	21st to end	Day	21% 9% 3 7% 5% 4 4 3 6% 5% 32%	2337
May	1st to 10th	Day	16% 7% 2 7% 5% 4 4 4 5% 7% 39%	4385
	11th to 20th	Day	15% 6% 3 6% 4 4 4 4 5% 7% 43%	4399
	21st to end	Day	16% 7% 2 7% 5% 4 4 4 5% 7% 38%	4824
June	1st to 10th	Day	13% 6% 2 5% 4 4 4 3 6% 8% 44%	2660
	11th to 20th	Day	14% 5% 2 5% 5% 5% 5% 4 5% 8% 41%	2660
	21st to end	Day	13% 5% 2 6% 5% 4 4 5% 7% 8% 40%	2660
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 5% 7% 10% 37%	4440
	11th to 20th	Day	5% 3 1 4 4 5% 5% 4 8% 10% 50%	4440
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 6% 8% 43%	4813
August	1st to 10th	Day	11% 5% 3 7% 5% 5% 5% 5% 6% 8% 40%	4346
	11th to 20th	Day	13% 5% 2 5% 3 4 4 3 5% 8% 46%	3923
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 5% 8% 43%	4180
September	1st to 10th	Day	14% 6% 2 5% 4 4 4 4 5% 8% 45%	2280
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 8% 46%	2252
	21st to end	Day	14% 6% 2 6% 4 3 4 4 5% 8% 42%	2073
October	1st to 10th	Day	14% 7% 1 6% 4 4 4 4 5% 6% 44%	1900
	11th to 20th	Day	19% 10% 3 7% 4 4 4 4 5% 7% 34%	1900
	21st to end	Day	18% 10% 3 8% 4 4 3 2 4 6% 38%	1926
November	1st to 10th	Day	14% 8% 3 6% 5% 4 4 3 5% 6% 41%	1753
	11th to 20th	Day	15% 12% 4 11% 6% 4 4 3 5% 6% 29%	1606
	21st to end	Day	15% 10% 3 6% 5% 4 5% 3 4 6% 38%	1520
December	1st to 10th	Day	14% 13% 5% 10% 6% 5% 5% 3 4 5% 30%	1520
	11th to 20th	Day	12% 17% 6% 8% 7% 5% 4 3 5% 6% 27%	1918
	21st to end	Day	21% 20% 7% 13% 5% 5% 4 2 3 3 17%	2783
January	1st to 10th	Night	11% 15% 9% 12% 5% 4 3 3 4 4 31%	4428
	11th to 20th	Night	10% 13% 6% 15% 7% 6% 7% 6% 7% 5% 20%	4440
	21st to end	Night	15% 18% 8% 11% 5% 4 4 3 4 5% 22%	4752
February	1st to 10th	Night	9% 14% 5% 10% 6% 5% 5% 3 5% 5% 34%	2470
	11th to 20th	Night	10% 10% 3 8% 5% 5% 4 4 6% 6% 40%	2343
	21st to end	Night	15% 12% 3 8% 6% 5% 4 4 5% 6% 34%	1884
March	1st to 10th	Night	11% 9% 2 5% 4 4 5% 4 5% 7% 45%	3733
	11th to 20th	Night	10% 7% 3 7% 5% 5% 5% 5% 5% 7% 41%	3557
	21st to end	Night	23% 11% 3 11% 5% 4 3 2 4 5% 29%	3565
April	1st to 10th	Night	19% 11% 3 7% 4 4 4 3 4 6% 34%	1900
	11th to 20th	Night	21% 8% 3 6% 5% 4 3 4 5% 5% 36%	1875
	21st to end	Night	18% 9% 2 6% 5% 4 3 4 6% 8% 36%	1843
May	1st to 10th	Night	16% 8% 3 8% 5% 5% 5% 3 6% 7% 34%	2519
	11th to 20th	Night	12% 6% 2 5% 4 4 4 3 6% 7% 48%	2506
	21st to end	Night	13% 7% 3 7% 4 4 4 3 6% 8% 42%	2743
June	1st to 10th	Night	11% 5% 2 7% 4 4 4 3 6% 8% 46%	1520
	11th to 20th	Night	13% 6% 2 7% 5% 5% 4 3 5% 8% 43%	1520
	21st to end	Night	9% 5% 2 6% 5% 4 4 3 6% 8% 47%	1520
July	1st to 10th	Night	14% 5% 2 5% 4 4 5% 3 6% 8% 44%	2530
	11th to 20th	Night	5% 3 1 4 4 4 4 4 6% 8% 55%	2530
	21st to end	Night	6% 4 2 6% 5% 4 5% 4 6% 8% 50%	2750
August	1st to 10th	Night	10% 5% 2 6% 4 5% 4 4 5% 8% 47%	2578
	11th to 20th	Night	10% 6% 2 4 4 4 4 4 6% 8% 47%	2911
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 5% 7% 48%	3476
September	1st to 10th	Night	11% 5% 1 5% 4 4 4 3 6% 6% 52%	1900
	11th to 20th	Night	12% 4 2 5% 4 3 3 3 4 8% 52%	1909
	21st to end	Night	13% 6% 2 5% 3 4 4 3 5% 6% 49%	2104
October	1st to 10th	Night	12% 6% 2 5% 3 4 3 3 4 7% 50%	2280
	11th to 20th	Night	17% 7% 2 6% 4 4 4 3 7% 7% 40%	2280
	21st to end	Night	18% 10% 2 8% 4 4 5% 4 5% 6% 34%	2670
November	1st to 10th	Night	15% 10% 2 6% 4 3 3 4 5% 7% 41%	2530
	11th to 20th	Night	13% 11% 5% 9% 6% 5% 5% 3 5% 5% 32%	2570
	21st to end	Night	16% 10% 3 8% 4 4 4 3 5% 6% 36%	2660
December	1st to 10th	Night	13% 12% 5% 9% 6% 5% 5% 4 6% 7% 30%	2660
	11th to 20th	Night	13% 16% 5% 11% 6% 5% 4 4 4 5% 27%	3279
	21st to end	Night	22% 17% 5% 11% 5% 3 3 2 4 5% 21%	4884

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	63% 5% 13% 15% 5%	2528
	11th to 20th	Day	62% 7% 11% 14% 5%	2530
	21st to end	Day	65% 5% 12% 14% 4	2912
February	1st to 10th	Day	51% 6% 14% 19% 10% 1	1710
	11th to 20th	Day	47% 6% 13% 24% 9% 2	1731
	21st to end	Day	53% 5% 11% 20% 9% 2	1570
March	1st to 10th	Day	39% 3 11% 26% 18% 2	3120
	11th to 20th	Day	40% 6% 12% 27% 14% 1	3434
	21st to end	Day	57% 5% 10% 19% 8% 1	4065
April	1st to 10th	Day	53% 6% 10% 19% 11% 1	2280
	11th to 20th	Day	52% 5% 7% 22% 12% 2	2254
	21st to end	Day	51% 7% 11% 19% 11% 1	2337
May	1st to 10th	Day	42% 7% 11% 25% 14%	4426
	11th to 20th	Day	38% 7% 11% 32% 12% 1	4403
	21st to end	Day	45% 7% 11% 21% 15% 2	4837
June	1st to 10th	Day	36% 7% 14% 26% 15% 2	2660
	11th to 20th	Day	41% 6% 13% 24% 15% 1	2660
	21st to end	Day	39% 8% 15% 25% 12% 2	2660
July	1st to 10th	Day	40% 8% 16% 27% 8% 1	4371
	11th to 20th	Day	24% 8% 16% 33% 16% 2	4365
	21st to end	Day	36% 8% 13% 24% 18% 1	4662
August	1st to 10th	Day	39% 8% 14% 26% 13% 1	4331
	11th to 20th	Day	35% 7% 11% 33% 13%	3962
	21st to end	Day	38% 6% 14% 28% 12% 1	4179
September	1st to 10th	Day	37% 6% 13% 27% 16%	2280
	11th to 20th	Day	36% 7% 14% 33% 9% 1	2252
	21st to end	Day	39% 7% 14% 27% 12%	2073
October	1st to 10th	Day	25% 5% 7% 41% 22%	3160
	11th to 20th	Day	40% 5% 11% 26% 16% 2	3140
	21st to end	Day	43% 3 14% 30% 10%	3151
November	1st to 10th	Day	42% 7% 14% 22% 15% 1	1753
	11th to 20th	Day	56% 5% 12% 18% 8% 1	1606
	21st to end	Day	47% 6% 17% 22% 7% 1	1520
December	1st to 10th	Day	56% 6% 14% 17% 6% 1	1520
	11th to 20th	Day	57% 5% 16% 13% 7% 2	1915
	21st to end	Day	73% 4 7% 11% 5%	2783
January	1st to 10th	Night	57% 5% 10% 20% 7% 1	4428
	11th to 20th	Night	63% 6% 10% 13% 7%	4440
	21st to end	Night	65% 5% 9% 16% 5%	4752
February	1st to 10th	Night	52% 6% 10% 21% 10% 2	2470
	11th to 20th	Night	44% 5% 13% 26% 10% 2	2344
	21st to end	Night	51% 5% 12% 20% 10% 2	1884
March	1st to 10th	Night	39% 6% 12% 29% 10% 4	3733
	11th to 20th	Night	41% 6% 10% 26% 16% 2	3557
	21st to end	Night	58% 4 8% 20% 9% 1	3565
April	1st to 10th	Night	51% 5% 9% 17% 16% 2	1900
	11th to 20th	Night	48% 5% 9% 20% 15% 3	1875
	21st to end	Night	44% 7% 12% 21% 14% 2	1843
May	1st to 10th	Night	47% 8% 14% 15% 17%	2543
	11th to 20th	Night	33% 8% 12% 27% 18% 2	2507
	21st to end	Night	39% 8% 12% 22% 18% 1	2751
June	1st to 10th	Night	33% 8% 14% 27% 17% 1	1520
	11th to 20th	Night	38% 6% 13% 23% 18% 2	1520
	21st to end	Night	33% 8% 13% 30% 12% 4	1520
July	1st to 10th	Night	37% 7% 17% 24% 12% 3	2490
	11th to 20th	Night	24% 8% 15% 34% 18% 1	2482
	21st to end	Night	31% 7% 15% 24% 20% 3	2662
August	1st to 10th	Night	35% 8% 13% 26% 17% 2	2569
	11th to 20th	Night	33% 8% 14% 29% 15% 1	2938
	21st to end	Night	33% 7% 14% 26% 18% 2	3476
September	1st to 10th	Night	31% 6% 13% 28% 21% 1	1900
	11th to 20th	Night	32% 6% 13% 33% 15% 1	1909
	21st to end	Night	36% 6% 11% 31% 16% 1	2104
October	1st to 10th	Night	26% 4 6% 36% 25% 3	3800
	11th to 20th	Night	31% 5% 12% 32% 20%	3779
	21st to end	Night	46% 6% 10% 23% 15% 1	4395
November	1st to 10th	Night	43% 6% 12% 25% 13% 2	2530
	11th to 20th	Night	52% 6% 13% 16% 11% 1	2570
	21st to end	Night	49% 5% 15% 24% 6% 1	2660
December	1st to 10th	Night	53% 7% 15% 20% 5%	2660
	11th to 20th	Night	60% 5% 12% 17% 6% 1	3281
	21st to end	Night	67% 4 9% 16% 4	4884

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	17% 14% 33% 23% 10% 2	270
	11th to 20th	Day	23% 14% 35% 22% 5% 1	270
	21st to end	Day	19% 14% 36% 24% 7%	297
February	1st to 10th	Day	14% 20% 41% 18% 5% 2	270
	11th to 20th	Day	16% 24% 34% 19% 7%	270
	21st to end	Day	18% 19% 42% 20% 2	225
March	1st to 10th	Day	17% 19% 38% 21% 6%	270
	11th to 20th	Day	21% 17% 31% 20% 8% 3	270
	21st to end	Day	25% 13% 31% 20% 8% 2	445
April	1st to 10th	Day	24% 16% 36% 19% 5%	460
	11th to 20th	Day	27% 17% 27% 19% 8% 1	452
	21st to end	Day	22% 15% 28% 22% 10% 2	460
May	1st to 10th	Day	20% 14% 33% 25% 6% 1	639
	11th to 20th	Day	19% 13% 29% 23% 12% 3	675
	21st to end	Day	19% 10% 27% 25% 13% 6%	734
June	1st to 10th	Day	12% 9% 29% 28% 17% 4	680
	11th to 20th	Day	15% 8% 32% 27% 13% 4	680
	21st to end	Day	15% 8% 28% 29% 14% 5%	680
July	1st to 10th	Day	8% 3 22% 29% 28% 9%	671
	11th to 20th	Day	8% 7% 26% 32% 18% 9%	668
	21st to end	Day	8% 4 27% 31% 23% 7%	739
August	1st to 10th	Day	9% 7% 21% 31% 24% 8%	676
	11th to 20th	Day	13% 6% 20% 27% 26% 9%	599
	21st to end	Day	13% 8% 23% 29% 22% 6%	539
September	1st to 10th	Day	17% 8% 23% 27% 19% 7%	490
	11th to 20th	Day	12% 8% 21% 33% 22% 5%	490
	21st to end	Day	16% 12% 23% 30% 15% 3	473
October	1st to 10th	Day	17% 14% 25% 27% 14% 3	300
	11th to 20th	Day	22% 20% 34% 16% 7% 1	300
	21st to end	Day	23% 15% 38% 17% 5% 1	330
November	1st to 10th	Day	19% 15% 33% 25% 7% 1	297
	11th to 20th	Day	19% 21% 36% 20% 3 1	270
	21st to end	Day	22% 14% 39% 18% 7%	270
December	1st to 10th	Day	17% 17% 39% 20% 6%	270
	11th to 20th	Day	18% 19% 40% 19% 5% 1	270
	21st to end	Day	26% 19% 37% 16% 2	297
January	1st to 10th	Night	15% 12% 37% 27% 8% 1	950
	11th to 20th	Night	19% 12% 35% 27% 5% 1	950
	21st to end	Night	19% 9% 36% 28% 7%	1045
February	1st to 10th	Night	15% 13% 37% 29% 6% 1	950
	11th to 20th	Night	14% 14% 40% 25% 7%	869
	21st to end	Night	21% 15% 35% 24% 4	628
March	1st to 10th	Night	18% 13% 34% 28% 7% 1	760
	11th to 20th	Night	18% 11% 36% 27% 7% 1	621
	21st to end	Night	22% 11% 29% 29% 8% 2	627
April	1st to 10th	Night	23% 14% 37% 22% 4	570
	11th to 20th	Night	23% 11% 32% 27% 6%	563
	21st to end	Night	21% 10% 33% 28% 8%	570
May	1st to 10th	Night	24% 10% 32% 29% 5%	570
	11th to 20th	Night	18% 8% 32% 33% 8% 1	561
	21st to end	Night	12% 6% 28% 38% 15% 1	617
June	1st to 10th	Night	12% 6% 29% 41% 11%	570
	11th to 20th	Night	16% 5% 30% 39% 11%	570
	21st to end	Night	9% 5% 26% 44% 15% 1	570
July	1st to 10th	Night	8% 3 19% 40% 27% 2	555
	11th to 20th	Night	9% 4 20% 41% 23% 3	552
	21st to end	Night	6% 2 20% 46% 24% 3	624
August	1st to 10th	Night	8% 1 18% 48% 24% 2	567
	11th to 20th	Night	10% 3 18% 38% 27% 4	564
	21st to end	Night	13% 4 19% 43% 18% 2	627
September	1st to 10th	Night	11% 6% 22% 39% 17% 5%	570
	11th to 20th	Night	12% 4 26% 34% 21% 3	579
	21st to end	Night	15% 8% 27% 33% 16% 1	760
October	1st to 10th	Night	14% 8% 30% 29% 17% 1	760
	11th to 20th	Night	20% 12% 32% 28% 8%	760
	21st to end	Night	22% 11% 31% 29% 7%	836
November	1st to 10th	Night	21% 10% 35% 25% 9% 1	779
	11th to 20th	Night	18% 17% 38% 21% 6%	860
	21st to end	Night	21% 15% 34% 23% 6%	950
December	1st to 10th	Night	19% 12% 40% 23% 5% 1	950
	11th to 20th	Night	23% 13% 34% 24% 6% 1	950
	21st to end	Night	27% 13% 31% 25% 4	1045

Page generated at 2024-11-07 05:55:45. Version ac07

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