Minakakis Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Minakakis Observatory clear sky chart from 2005-11-06 to 2024-02-05.

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% 4 7% 7% 4 5% 5% 6% 7% 32%	78495
	Night	14% 9% 4 7% 6% 4 5% 5% 6% 7% 33%	80336
Transparency	Day	49% 9% 13% 18% 9% 1	78212
	Night	48% 10% 13% 18% 10% 1	80154
Seeing	Day	18% 16% 30% 22% 10% 3	13650
	Night	18% 14% 32% 25% 10% 1	22963

By Month

Percentage Cloud Cover NE (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	14% 15% 7% 10% 7% 4 5% 4 5% 6% 25%	2517
	11th to 20th	Day	11% 17% 8% 14% 10% 5% 5% 5% 4 6% 16%	2812
	21st to end	Day	21% 18% 6% 9% 8% 4 5% 4 4 4 16%	3124
February	1st to 10th	Day	13% 14% 5% 11% 10% 4 5% 5% 5% 6% 21%	1656
	11th to 20th	Day	11% 12% 6% 11% 9% 5% 5% 4 6% 6% 25%	1573
	21st to end	Day	18% 12% 5% 10% 7% 3 5% 4 5% 6% 26%	1391
March	1st to 10th	Day	12% 10% 5% 10% 8% 4 6% 4 5% 6% 31%	1977
	11th to 20th	Day	12% 10% 6% 8% 7% 4 5% 5% 4 5% 32%	1980
	21st to end	Day	15% 10% 5% 7% 7% 3 5% 4 5% 5% 32%	2178
April	1st to 10th	Day	15% 10% 5% 7% 6% 4 5% 5% 6% 7% 29%	2106
	11th to 20th	Day	17% 9% 4 6% 5% 4 4 4 5% 6% 37%	2225
	21st to end	Day	19% 9% 4 6% 7% 2 5% 4 5% 7% 33%	2340
May	1st to 10th	Day	15% 7% 4 8% 6% 3 4 5% 6% 6% 35%	2340
	11th to 20th	Day	15% 6% 3 6% 6% 3 5% 6% 5% 6% 39%	2428
	21st to end	Day	10% 5% 3 5% 6% 3 4 6% 6% 9% 42%	2725
June	1st to 10th	Day	13% 6% 3 5% 6% 3 5% 6% 6% 8% 39%	2520
	11th to 20th	Day	11% 5% 3 5% 6% 3 6% 5% 7% 10% 40%	2538
	21st to end	Day	12% 5% 2 5% 5% 3 5% 6% 6% 10% 40%	2700
July	1st to 10th	Day	7% 4 2 4 6% 4 6% 6% 7% 9% 45%	2606
	11th to 20th	Day	10% 5% 3 5% 5% 3 6% 6% 8% 10% 39%	2506
	21st to end	Day	9% 5% 3 6% 6% 4 7% 6% 7% 10% 38%	2547
August	1st to 10th	Day	8% 5% 2 6% 6% 4 5% 7% 7% 11% 39%	2327
	11th to 20th	Day	7% 5% 3 7% 8% 5% 6% 6% 7% 9% 37%	2303
	21st to end	Day	12% 6% 2 5% 5% 3 6% 5% 8% 9% 40%	2494
September	1st to 10th	Day	12% 6% 2 5% 6% 4 5% 6% 5% 9% 40%	2160
	11th to 20th	Day	11% 5% 3 6% 5% 3 4 5% 5% 9% 44%	2026
	21st to end	Day	13% 5% 3 6% 7% 4 6% 6% 7% 8% 34%	1961
October	1st to 10th	Day	18% 9% 3 6% 5% 4 4 5% 5% 7% 34%	1800
	11th to 20th	Day	19% 9% 3 8% 7% 4 5% 5% 5% 7% 28%	1800
	21st to end	Day	23% 11% 4 8% 6% 5% 5% 5% 5% 6% 23%	1980
November	1st to 10th	Day	13% 9% 4 7% 6% 3 6% 5% 7% 7% 32%	1617
	11th to 20th	Day	13% 10% 4 9% 8% 4 6% 5% 6% 8% 26%	1520
	21st to end	Day	16% 12% 6% 8% 7% 4 6% 5% 6% 7% 23%	1520
December	1st to 10th	Day	14% 16% 7% 11% 8% 5% 6% 5% 6% 6% 17%	1520
	11th to 20th	Day	16% 15% 5% 9% 8% 4 6% 5% 5% 6% 20%	1906
	21st to end	Day	28% 18% 7% 11% 6% 3 4 4 4 5% 10%	2772
January	1st to 10th	Night	16% 13% 6% 9% 8% 5% 5% 5% 5% 6% 22%	4429
	11th to 20th	Night	12% 12% 6% 11% 10% 6% 6% 6% 6% 10% 15%	4143
	21st to end	Night	20% 11% 7% 10% 7% 4 5% 4 5% 7% 20%	4532
February	1st to 10th	Night	13% 12% 4 8% 9% 5% 5% 5% 6% 7% 25%	2399
	11th to 20th	Night	12% 11% 6% 9% 8% 5% 7% 5% 5% 7% 27%	2273
	21st to end	Night	13% 11% 4 9% 8% 3 6% 5% 5% 7% 29%	1862
March	1st to 10th	Night	13% 7% 4 7% 6% 4 6% 5% 6% 8% 34%	1970
	11th to 20th	Night	13% 10% 5% 7% 6% 3 5% 5% 6% 6% 35%	1979
	21st to end	Night	15% 9% 4 6% 6% 3 5% 4 5% 5% 38%	2178
April	1st to 10th	Night	16% 8% 4 6% 6% 3 5% 6% 5% 6% 33%	1853
	11th to 20th	Night	14% 7% 3 6% 6% 4 5% 5% 6% 6% 39%	1700
	21st to end	Night	15% 9% 3 6% 6% 3 4 4 6% 7% 37%	1620
May	1st to 10th	Night	15% 8% 2 5% 5% 4 5% 5% 5% 7% 40%	1620
	11th to 20th	Night	15% 5% 2 5% 5% 3 4 5% 5% 7% 46%	1464
	21st to end	Night	9% 3 2 4 4 2 5% 4 6% 8% 52%	1550
June	1st to 10th	Night	10% 4 2 6% 5% 4 4 6% 6% 9% 44%	1440
	11th to 20th	Night	10% 5% 3 5% 5% 3 4 5% 6% 9% 44%	1413
	21st to end	Night	10% 4 3 5% 5% 3 4 5% 6% 7% 48%	1260
July	1st to 10th	Night	6% 4 2 3 4 2 5% 4 4 8% 60%	1345
	11th to 20th	Night	8% 4 2 5% 5% 2 4 5% 6% 8% 51%	1450
	21st to end	Night	7% 3 2 4 4 3 5% 5% 7% 8% 51%	1771
August	1st to 10th	Night	7% 4 2 6% 5% 2 4 5% 6% 7% 50%	1611
	11th to 20th	Night	7% 3 3 4 4 2 4 6% 6% 9% 53%	1598
	21st to end	Night	9% 5% 2 5% 5% 3 5% 5% 6% 7% 48%	1843
September	1st to 10th	Night	9% 5% 2 5% 5% 3 5% 6% 6% 8% 47%	1800
	11th to 20th	Night	11% 6% 1 3 3 2 3 4 5% 7% 54%	1930
	21st to end	Night	13% 6% 3 6% 6% 4 6% 4 5% 7% 42%	1998
October	1st to 10th	Night	16% 7% 2 7% 4 2 4 5% 5% 7% 39%	2160
	11th to 20th	Night	16% 9% 3 7% 5% 4 4 5% 5% 7% 34%	2160
	21st to end	Night	21% 9% 4 7% 5% 3 5% 5% 6% 7% 29%	2376
November	1st to 10th	Night	14% 7% 3 6% 5% 4 5% 4 6% 7% 38%	2457
	11th to 20th	Night	14% 10% 4 7% 6% 4 5% 6% 6% 8% 30%	2660
	21st to end	Night	17% 10% 4 8% 5% 3 5% 5% 7% 8% 28%	2660
December	1st to 10th	Night	18% 13% 5% 8% 6% 4 5% 5% 6% 7% 23%	2660
	11th to 20th	Night	15% 15% 5% 10% 6% 4 6% 6% 6% 7% 20%	3288
	21st to end	Night	27% 17% 7% 10% 6% 3 5% 4 5% 5% 12%	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	57% 12% 14% 10% 7%	2518
	11th to 20th	Day	68% 9% 11% 9% 4	2812
	21st to end	Day	70% 8% 9% 7% 4 1	3124
February	1st to 10th	Day	64% 10% 11% 12% 3 1	1656
	11th to 20th	Day	58% 8% 11% 13% 7% 2	1582
	21st to end	Day	60% 7% 12% 13% 7% 1	1391
March	1st to 10th	Day	53% 8% 14% 15% 9% 1	1980
	11th to 20th	Day	52% 9% 10% 17% 10% 2	1980
	21st to end	Day	52% 7% 11% 17% 11% 2	2178
April	1st to 10th	Day	53% 8% 12% 16% 10% 1	2106
	11th to 20th	Day	46% 7% 12% 20% 13% 1	2225
	21st to end	Day	51% 7% 11% 17% 11% 2	2340
May	1st to 10th	Day	47% 8% 12% 21% 12% 1	2340
	11th to 20th	Day	43% 9% 12% 23% 12% 1	2432
	21st to end	Day	37% 9% 17% 21% 14% 2	2725
June	1st to 10th	Day	39% 10% 12% 22% 15% 2	2520
	11th to 20th	Day	38% 9% 14% 23% 15% 1	2538
	21st to end	Day	37% 10% 15% 23% 15%	2700
July	1st to 10th	Day	32% 10% 14% 24% 17% 3	2536
	11th to 20th	Day	35% 10% 19% 25% 11% 1	2431
	21st to end	Day	38% 11% 16% 21% 13% 2	2405
August	1st to 10th	Day	35% 11% 19% 23% 11% 2	2314
	11th to 20th	Day	38% 11% 18% 21% 11%	2303
	21st to end	Day	38% 9% 16% 25% 11% 1	2494
September	1st to 10th	Day	39% 10% 15% 25% 11% 1	2160
	11th to 20th	Day	35% 8% 15% 28% 13%	2026
	21st to end	Day	43% 11% 15% 23% 8% 1	1961
October	1st to 10th	Day	48% 9% 14% 17% 10% 1	1800
	11th to 20th	Day	52% 9% 14% 18% 6% 1	1800
	21st to end	Day	60% 9% 12% 13% 6% 1	1980
November	1st to 10th	Day	46% 10% 16% 20% 7% 1	1617
	11th to 20th	Day	52% 11% 16% 14% 6%	1520
	21st to end	Day	58% 11% 15% 13% 4	1520
December	1st to 10th	Day	65% 11% 11% 10% 3	1520
	11th to 20th	Day	62% 10% 12% 11% 4	1906
	21st to end	Day	75% 10% 8% 6% 1	2772
January	1st to 10th	Night	58% 13% 12% 13% 4	4429
	11th to 20th	Night	60% 18% 11% 7% 3	4143
	21st to end	Night	63% 8% 13% 11% 4 1	4532
February	1st to 10th	Night	58% 9% 12% 16% 4 1	2399
	11th to 20th	Night	57% 7% 12% 15% 8%	2275
	21st to end	Night	54% 9% 13% 16% 7%	1862
March	1st to 10th	Night	46% 9% 14% 20% 9% 2	1980
	11th to 20th	Night	49% 7% 11% 19% 11% 2	1980
	21st to end	Night	48% 6% 9% 19% 16% 2	2178
April	1st to 10th	Night	49% 8% 10% 18% 14% 1	1853
	11th to 20th	Night	44% 7% 11% 20% 16% 2	1700
	21st to end	Night	46% 7% 11% 18% 15% 3	1620
May	1st to 10th	Night	43% 7% 11% 22% 15% 2	1620
	11th to 20th	Night	38% 7% 12% 25% 15% 4	1465
	21st to end	Night	30% 9% 15% 25% 19% 4	1551
June	1st to 10th	Night	35% 9% 13% 24% 18% 1	1440
	11th to 20th	Night	35% 7% 14% 23% 19% 2	1413
	21st to end	Night	35% 8% 15% 26% 17% 1	1260
July	1st to 10th	Night	24% 8% 13% 25% 27% 4	1306
	11th to 20th	Night	31% 7% 14% 29% 18% 2	1402
	21st to end	Night	29% 10% 15% 27% 17% 2	1672
August	1st to 10th	Night	31% 9% 16% 30% 12% 2	1600
	11th to 20th	Night	25% 9% 19% 31% 14% 2	1598
	21st to end	Night	33% 9% 14% 27% 15% 2	1843
September	1st to 10th	Night	33% 9% 16% 26% 14% 1	1800
	11th to 20th	Night	30% 7% 13% 32% 18% 1	1930
	21st to end	Night	41% 9% 12% 26% 11% 1	1998
October	1st to 10th	Night	42% 10% 12% 21% 15% 1	2160
	11th to 20th	Night	48% 9% 14% 21% 8%	2160
	21st to end	Night	53% 9% 13% 16% 9% 1	2376
November	1st to 10th	Night	43% 8% 15% 21% 12% 1	2457
	11th to 20th	Night	49% 11% 15% 16% 7% 1	2660
	21st to end	Night	51% 12% 18% 14% 4	2660
December	1st to 10th	Night	57% 13% 13% 13% 4	2660
	11th to 20th	Night	58% 13% 14% 12% 3	3288
	21st to end	Night	73% 10% 9% 6% 2	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	21% 26% 32% 17% 5% 1	180
	11th to 20th	Day	22% 31% 32% 11% 3	263
	21st to end	Day	24% 29% 30% 14% 3	297
February	1st to 10th	Day	23% 35% 32% 8% 3	252
	11th to 20th	Day	22% 34% 35% 8% 1	240
	21st to end	Day	36% 25% 34% 5%	198
March	1st to 10th	Day	22% 22% 33% 18% 5%	420
	11th to 20th	Day	20% 23% 36% 15% 5%	420
	21st to end	Day	28% 17% 33% 16% 5% 1	462
April	1st to 10th	Day	18% 22% 37% 16% 6%	420
	11th to 20th	Day	25% 21% 28% 16% 7% 2	412
	21st to end	Day	24% 17% 35% 16% 7% 2	420
May	1st to 10th	Day	22% 15% 31% 18% 9% 4	423
	11th to 20th	Day	16% 13% 33% 23% 11% 4	447
	21st to end	Day	14% 9% 30% 26% 15% 6%	485
June	1st to 10th	Day	13% 14% 34% 28% 10% 2	450
	11th to 20th	Day	14% 13% 26% 30% 15% 2	468
	21st to end	Day	15% 9% 32% 31% 10% 3	630
July	1st to 10th	Day	8% 5% 29% 34% 19% 5%	531
	11th to 20th	Day	13% 8% 25% 29% 17% 8%	444
	21st to end	Day	8% 6% 32% 36% 15% 4	488
August	1st to 10th	Day	9% 7% 25% 30% 20% 9%	446
	11th to 20th	Day	8% 5% 27% 28% 23% 9%	439
	21st to end	Day	13% 8% 26% 29% 17% 7%	495
September	1st to 10th	Day	14% 8% 25% 26% 18% 8%	450
	11th to 20th	Day	10% 8% 24% 26% 21% 10%	450
	21st to end	Day	15% 13% 27% 24% 15% 6%	450
October	1st to 10th	Day	22% 15% 28% 19% 13% 4	450
	11th to 20th	Day	21% 22% 33% 15% 7% 1	450
	21st to end	Day	28% 20% 29% 17% 5%	495
November	1st to 10th	Day	20% 27% 29% 18% 5% 1	257
	11th to 20th	Day	25% 28% 28% 12% 6% 1	180
	21st to end	Day	23% 23% 39% 13% 2	180
December	1st to 10th	Day	26% 28% 31% 14% 1	180
	11th to 20th	Day	29% 30% 28% 11% 2	180
	21st to end	Day	28% 27% 33% 11% 2	198
January	1st to 10th	Night	21% 24% 35% 14% 4 1	760
	11th to 20th	Night	25% 22% 31% 18% 3	760
	21st to end	Night	17% 18% 39% 20% 6%	836
February	1st to 10th	Night	20% 25% 36% 17% 2	739
	11th to 20th	Night	21% 20% 38% 17% 4	703
	21st to end	Night	19% 22% 37% 18% 3	592
March	1st to 10th	Night	20% 17% 37% 21% 5%	720
	11th to 20th	Night	20% 19% 35% 20% 5%	720
	21st to end	Night	20% 14% 34% 24% 7%	792
April	1st to 10th	Night	23% 14% 36% 24% 3	720
	11th to 20th	Night	18% 16% 35% 23% 7% 2	636
	21st to end	Night	19% 11% 34% 26% 10%	540
May	1st to 10th	Night	17% 8% 32% 28% 13% 2	540
	11th to 20th	Night	16% 7% 32% 31% 12% 1	403
	21st to end	Night	11% 6% 29% 35% 19%	389
June	1st to 10th	Night	13% 6% 31% 36% 14% 1	360
	11th to 20th	Night	10% 8% 31% 36% 14% 1	360
	21st to end	Night	12% 5% 29% 39% 15%	360
July	1st to 10th	Night	6% 5% 24% 41% 23% 1	350
	11th to 20th	Night	10% 4 30% 35% 19% 1	358
	21st to end	Night	9% 3 26% 40% 20% 2	591
August	1st to 10th	Night	9% 2 22% 40% 24% 2	537
	11th to 20th	Night	7% 4 19% 42% 26% 3	534
	21st to end	Night	11% 4 29% 31% 23% 2	655
September	1st to 10th	Night	12% 8% 25% 32% 19% 5%	720
	11th to 20th	Night	13% 6% 26% 27% 24% 5%	720
	21st to end	Night	17% 10% 22% 30% 18% 4	720
October	1st to 10th	Night	18% 10% 29% 24% 16% 2	720
	11th to 20th	Night	21% 15% 32% 24% 7% 1	720
	21st to end	Night	26% 16% 31% 23% 4	792
November	1st to 10th	Night	21% 13% 31% 25% 10% 1	740
	11th to 20th	Night	18% 20% 35% 19% 7% 1	760
	21st to end	Night	23% 18% 33% 21% 4	760
December	1st to 10th	Night	27% 20% 35% 14% 4	760
	11th to 20th	Night	22% 21% 39% 14% 3	760
	21st to end	Night	29% 21% 31% 18% 2	836

Page generated at 2024-02-02 05:20:30. Version ac07

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