Osservatorio Aucello
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Osservatorio Aucello clear sky chart from 2005-11-06 to 2024-07-03.

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	12% 8% 3 6% 4 4 4 3 5% 7% 44%	89518
	Night	11% 7% 3 6% 4 4 4 3 5% 6% 48%	89706
Transparency	Day	39% 5% 13% 26% 15% 2	89292
	Night	38% 4 12% 26% 18% 3	89537
Seeing	Day	14% 11% 29% 27% 15% 3	15169
	Night	14% 10% 33% 31% 11% 1	25070

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	14% 11% 3 9% 4 4 4 3 5% 6% 38%	2847
	11th to 20th	Day	9% 11% 4 9% 6% 7% 5% 3 3 5% 38%	2850
	21st to end	Day	14% 15% 5% 9% 4 3 4 2 4 6% 34%	3135
February	1st to 10th	Day	15% 11% 4 7% 5% 5% 3 3 4 6% 38%	1710
	11th to 20th	Day	12% 10% 3 7% 5% 3 4 3 5% 6% 41%	1664
	21st to end	Day	11% 9% 3 6% 4 4 4 3 5% 6% 44%	1624
March	1st to 10th	Day	13% 10% 3 6% 3 3 4 3 3 5% 47%	3436
	11th to 20th	Day	12% 7% 2 4 3 3 4 3 4 6% 53%	3480
	21st to end	Day	15% 12% 5% 6% 5% 4 4 3 4 6% 36%	3814
April	1st to 10th	Day	13% 8% 3 6% 4 3 4 3 5% 7% 45%	2191
	11th to 20th	Day	14% 8% 3 7% 4 5% 4 4 5% 6% 41%	2254
	21st to end	Day	20% 8% 2 7% 5% 5% 4 3 4 5% 37%	2413
May	1st to 10th	Day	15% 9% 3 7% 4 4 4 3 5% 7% 38%	4082
	11th to 20th	Day	16% 8% 2 6% 4 4 5% 3 6% 7% 39%	4082
	21st to end	Day	13% 6% 2 6% 4 4 4 4 6% 7% 44%	4558
June	1st to 10th	Day	7% 4 2 5% 4 5% 5% 5% 7% 10% 48%	2660
	11th to 20th	Day	7% 4 3 5% 4 5% 5% 4 7% 9% 47%	2660
	21st to end	Day	7% 3 2 5% 4 4 5% 4 6% 8% 52%	2633
July	1st to 10th	Day	9% 6% 2 5% 4 4 5% 4 8% 9% 44%	2367
	11th to 20th	Day	4 2 1 4 4 4 5% 4 9% 9% 54%	2340
	21st to end	Day	8% 5% 1 6% 4 5% 6% 5% 7% 8% 44%	2546
August	1st to 10th	Day	8% 4 2 6% 5% 4 5% 5% 7% 10% 45%	2328
	11th to 20th	Day	8% 4 2 6% 4 4 4 4 6% 9% 50%	2301
	21st to end	Day	8% 5% 2 5% 3 3 5% 4 6% 7% 53%	2430
September	1st to 10th	Day	13% 5% 2 5% 3 3 3 4 5% 7% 52%	2160
	11th to 20th	Day	9% 5% 2 5% 5% 4 4 4 5% 6% 50%	1994
	21st to end	Day	8% 4 2 6% 3 3 3 4 5% 6% 55%	1971
October	1st to 10th	Day	12% 6% 2 5% 3 3 4 2 6% 7% 51%	1800
	11th to 20th	Day	12% 6% 2 4 3 3 3 2 4 5% 56%	1800
	21st to end	Day	15% 7% 3 6% 3 3 4 2 4 6% 48%	1980
November	1st to 10th	Day	9% 5% 2 5% 3 3 4 3 4 6% 55%	1858
	11th to 20th	Day	14% 6% 3 4 4 3 3 2 4 7% 50%	1649
	21st to end	Day	14% 8% 2 7% 3 4 3 3 3 5% 48%	1520
December	1st to 10th	Day	9% 9% 3 5% 5% 4 3 3 5% 8% 45%	1520
	11th to 20th	Day	11% 10% 4 8% 4 4 4 3 4 6% 41%	1918
	21st to end	Day	16% 14% 8% 13% 4 3 4 3 4 5% 26%	2943
January	1st to 10th	Night	9% 9% 3 14% 5% 4 4 3 3 5% 40%	4108
	11th to 20th	Night	10% 9% 4 8% 6% 8% 6% 4 4 5% 37%	4120
	21st to end	Night	16% 13% 5% 10% 4 3 3 3 3 5% 36%	4532
February	1st to 10th	Night	11% 11% 3 7% 5% 4 3 3 5% 7% 39%	2470
	11th to 20th	Night	11% 9% 3 7% 5% 4 4 3 4 6% 43%	2403
	21st to end	Night	12% 7% 3 7% 5% 4 3 3 5% 5% 47%	1843
March	1st to 10th	Night	13% 9% 3 4 3 3 3 3 4 5% 50%	3419
	11th to 20th	Night	10% 7% 2 4 2 3 3 3 5% 7% 55%	3480
	21st to end	Night	15% 9% 4 8% 5% 4 4 3 4 6% 38%	3817
April	1st to 10th	Night	10% 7% 2 6% 4 3 3 3 6% 6% 50%	1987
	11th to 20th	Night	13% 7% 3 6% 4 3 3 3 5% 6% 47%	1875
	21st to end	Night	17% 7% 3 6% 4 3 3 4 4 5% 44%	1762
May	1st to 10th	Night	15% 7% 3 6% 4 4 4 4 6% 6% 41%	2823
	11th to 20th	Night	16% 6% 2 6% 4 4 4 4 5% 7% 44%	2823
	21st to end	Night	12% 5% 2 4 3 3 3 3 5% 7% 52%	3005
June	1st to 10th	Night	5% 3 1 4 3 5% 4 5% 6% 9% 55%	1520
	11th to 20th	Night	5% 4 2 4 3 4 4 5% 7% 10% 52%	1520
	21st to end	Night	5% 3 1 3 3 3 3 4 6% 9% 61%	1540
July	1st to 10th	Night	6% 4 1 5% 3 3 5% 4 7% 10% 52%	1638
	11th to 20th	Night	3 3 1 3 3 4 4 4 7% 9% 60%	1620
	21st to end	Night	7% 4 2 5% 4 4 5% 4 7% 10% 49%	1772
August	1st to 10th	Night	4 2 1 4 3 5% 5% 5% 7% 9% 54%	1611
	11th to 20th	Night	6% 5% 1 4 3 3 4 4 5% 7% 59%	1600
	21st to end	Night	5% 4 1 4 4 3 3 2 5% 7% 61%	1926
September	1st to 10th	Night	10% 5% 2 5% 3 3 3 3 4 5% 56%	1800
	11th to 20th	Night	9% 5% 2 4 3 3 4 4 6% 7% 53%	1963
	21st to end	Night	6% 4 2 5% 4 4 3 3 5% 5% 59%	1980
October	1st to 10th	Night	10% 5% 1 5% 3 3 3 4 4 5% 56%	2150
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 4 5% 56%	2160
	21st to end	Night	16% 7% 3 5% 2 3 3 2 4 4 51%	2376
November	1st to 10th	Night	9% 5% 2 4 3 3 3 2 4 5% 61%	2220
	11th to 20th	Night	10% 7% 2 3 3 3 3 3 5% 7% 54%	2524
	21st to end	Night	15% 7% 2 4 3 3 3 3 3 5% 52%	2660
December	1st to 10th	Night	11% 8% 3 5% 4 4 3 4 5% 6% 46%	2660
	11th to 20th	Night	11% 8% 3 7% 4 4 4 3 5% 6% 45%	3279
	21st to end	Night	18% 17% 5% 10% 4 4 3 3 3 4 29%	4720

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	47% 4 10% 25% 13% 1	2848
	11th to 20th	Day	51% 3 12% 22% 11% 1	2850
	21st to end	Day	53% 3 11% 17% 15% 1	3135
February	1st to 10th	Day	49% 4 12% 22% 10% 3	1710
	11th to 20th	Day	44% 5% 12% 22% 14% 2	1673
	21st to end	Day	41% 4 11% 24% 16% 4	1624
March	1st to 10th	Day	41% 4 9% 22% 22% 3	3436
	11th to 20th	Day	33% 4 13% 28% 19% 3	3480
	21st to end	Day	49% 4 16% 24% 6% 1	3814
April	1st to 10th	Day	40% 5% 12% 24% 17% 2	2191
	11th to 20th	Day	44% 5% 12% 23% 16% 1	2254
	21st to end	Day	50% 4 11% 24% 10% 1	2413
May	1st to 10th	Day	46% 6% 10% 23% 13% 2	4120
	11th to 20th	Day	44% 5% 14% 22% 14%	4086
	21st to end	Day	38% 6% 12% 31% 12% 2	4571
June	1st to 10th	Day	29% 8% 18% 29% 15% 2	2660
	11th to 20th	Day	32% 5% 16% 30% 16% 2	2660
	21st to end	Day	28% 6% 15% 30% 16% 4	2633
July	1st to 10th	Day	33% 7% 17% 25% 16% 3	2303
	11th to 20th	Day	24% 7% 18% 29% 18% 4	2271
	21st to end	Day	32% 7% 14% 32% 14% 1	2405
August	1st to 10th	Day	32% 8% 18% 29% 13% 1	2314
	11th to 20th	Day	30% 6% 14% 32% 16% 2	2301
	21st to end	Day	29% 7% 12% 27% 19% 6%	2430
September	1st to 10th	Day	32% 5% 13% 26% 18% 6%	2160
	11th to 20th	Day	32% 6% 11% 25% 23% 2	1994
	21st to end	Day	29% 4 10% 30% 24% 3	1971
October	1st to 10th	Day	33% 4 12% 29% 20% 3	1800
	11th to 20th	Day	32% 3 8% 28% 24% 5%	1800
	21st to end	Day	40% 3 12% 21% 19% 5%	1980
November	1st to 10th	Day	31% 4 12% 29% 19% 5%	1858
	11th to 20th	Day	36% 3 11% 27% 21% 3	1649
	21st to end	Day	41% 3 9% 26% 19% 1	1520
December	1st to 10th	Day	38% 4 14% 30% 13% 1	1520
	11th to 20th	Day	45% 3 13% 26% 11% 2	1915
	21st to end	Day	60% 5% 10% 17% 7% 2	2943
January	1st to 10th	Night	47% 4 14% 22% 12% 1	4108
	11th to 20th	Night	51% 3 11% 23% 12% 1	4120
	21st to end	Night	52% 3 12% 20% 11% 1	4532
February	1st to 10th	Night	45% 5% 11% 23% 14% 3	2470
	11th to 20th	Night	42% 4 12% 23% 17% 3	2404
	21st to end	Night	41% 3 9% 23% 18% 6%	1843
March	1st to 10th	Night	37% 3 11% 24% 21% 3	3419
	11th to 20th	Night	29% 4 10% 26% 26% 4	3480
	21st to end	Night	47% 5% 17% 22% 8% 1	3817
April	1st to 10th	Night	35% 4 11% 24% 22% 4	1987
	11th to 20th	Night	39% 3 9% 29% 17% 4	1875
	21st to end	Night	43% 4 11% 25% 15% 2	1762
May	1st to 10th	Night	43% 6% 15% 20% 16% 1	2850
	11th to 20th	Night	40% 5% 14% 27% 13% 1	2824
	21st to end	Night	31% 5% 12% 30% 21% 1	3013
June	1st to 10th	Night	23% 7% 19% 32% 16% 3	1520
	11th to 20th	Night	26% 6% 14% 33% 19% 2	1520
	21st to end	Night	20% 5% 14% 34% 23% 4	1540
July	1st to 10th	Night	26% 5% 18% 32% 16% 4	1593
	11th to 20th	Night	19% 6% 15% 34% 22% 4	1566
	21st to end	Night	27% 7% 13% 33% 19% 2	1673
August	1st to 10th	Night	24% 6% 18% 34% 15% 3	1601
	11th to 20th	Night	25% 4 12% 34% 23% 2	1600
	21st to end	Night	24% 5% 10% 29% 25% 7%	1926
September	1st to 10th	Night	30% 4 11% 28% 19% 7%	1800
	11th to 20th	Night	29% 5% 10% 26% 25% 5%	1963
	21st to end	Night	27% 5% 7% 28% 28% 5%	1980
October	1st to 10th	Night	30% 4 9% 27% 24% 6%	2150
	11th to 20th	Night	32% 3 7% 28% 23% 8%	2160
	21st to end	Night	38% 3 8% 23% 24% 4	2376
November	1st to 10th	Night	27% 3 13% 27% 24% 6%	2220
	11th to 20th	Night	32% 3 10% 28% 24% 5%	2524
	21st to end	Night	36% 3 10% 29% 19% 3	2660
December	1st to 10th	Night	38% 4 13% 27% 16% 1	2660
	11th to 20th	Night	40% 3 10% 28% 16% 2	3281
	21st to end	Night	60% 4 7% 19% 9% 2	4720

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	23% 16% 37% 19% 6%	270
	11th to 20th	Day	26% 19% 37% 17% 2	270
	21st to end	Day	15% 16% 46% 19% 3	297
February	1st to 10th	Day	24% 18% 40% 14% 3	270
	11th to 20th	Day	18% 21% 42% 15% 3 1	270
	21st to end	Day	13% 32% 41% 12% 3	225
March	1st to 10th	Day	17% 20% 46% 14% 3	270
	11th to 20th	Day	27% 15% 37% 17% 3	270
	21st to end	Day	30% 24% 29% 14% 3	297
April	1st to 10th	Day	21% 20% 36% 16% 6%	371
	11th to 20th	Day	19% 17% 40% 19% 5% 1	452
	21st to end	Day	22% 18% 34% 18% 8%	593
May	1st to 10th	Day	19% 15% 38% 20% 8% 1	653
	11th to 20th	Day	19% 11% 28% 26% 13% 2	675
	21st to end	Day	16% 10% 31% 25% 14% 4	734
June	1st to 10th	Day	6% 5% 22% 34% 26% 6%	680
	11th to 20th	Day	9% 4 29% 35% 19% 4	680
	21st to end	Day	5% 8% 35% 36% 15% 2	680
July	1st to 10th	Day	11% 4 13% 33% 28% 10%	632
	11th to 20th	Day	5% 3 17% 41% 27% 7%	618
	21st to end	Day	8% 3 15% 40% 26% 7%	684
August	1st to 10th	Day	7% 3 17% 40% 29% 4	626
	11th to 20th	Day	7% 3 17% 39% 27% 7%	615
	21st to end	Day	9% 2 15% 31% 34% 9%	549
September	1st to 10th	Day	14% 3 16% 38% 24% 6%	450
	11th to 20th	Day	6% 2 21% 43% 21% 7%	284
	21st to end	Day	9% 6% 28% 34% 19% 4	270
October	1st to 10th	Day	14% 7% 34% 24% 15% 6%	270
	11th to 20th	Day	12% 17% 44% 20% 6% 1	270
	21st to end	Day	23% 15% 37% 21% 4 1	297
November	1st to 10th	Day	14% 17% 32% 29% 7% 1	270
	11th to 20th	Day	19% 17% 33% 21% 9% 1	270
	21st to end	Day	20% 17% 33% 23% 6%	270
December	1st to 10th	Day	10% 19% 39% 26% 3 3	270
	11th to 20th	Day	20% 18% 38% 17% 7% 1	270
	21st to end	Day	21% 28% 34% 17%	297
January	1st to 10th	Night	14% 15% 38% 26% 6%	950
	11th to 20th	Night	15% 16% 39% 25% 5% 1	950
	21st to end	Night	14% 14% 42% 27% 3	1045
February	1st to 10th	Night	18% 13% 42% 23% 3	950
	11th to 20th	Night	16% 15% 40% 26% 3	929
	21st to end	Night	17% 15% 44% 19% 3 1	587
March	1st to 10th	Night	14% 14% 43% 24% 5%	570
	11th to 20th	Night	19% 13% 35% 26% 6% 1	570
	21st to end	Night	25% 14% 33% 24% 3	627
April	1st to 10th	Night	13% 15% 39% 27% 6%	570
	11th to 20th	Night	19% 13% 35% 28% 5%	563
	21st to end	Night	21% 12% 38% 24% 6%	570
May	1st to 10th	Night	17% 9% 37% 31% 6%	570
	11th to 20th	Night	15% 7% 28% 36% 12% 1	561
	21st to end	Night	12% 7% 29% 35% 15% 2	617
June	1st to 10th	Night	7% 3 21% 45% 22% 2	570
	11th to 20th	Night	6% 3 30% 43% 18% 1	570
	21st to end	Night	5% 3 34% 46% 12% 1	570
July	1st to 10th	Night	8% 2 12% 46% 29% 4	531
	11th to 20th	Night	3 2 16% 48% 29% 3	522
	21st to end	Night	7% 2 13% 46% 30% 2	591
August	1st to 10th	Night	3 2 15% 47% 31% 1	537
	11th to 20th	Night	7% 3 12% 46% 29% 2	534
	21st to end	Night	6% 2 14% 40% 36% 2	594
September	1st to 10th	Night	12% 4 20% 40% 21% 4	540
	11th to 20th	Night	11% 2 21% 39% 24% 4	540
	21st to end	Night	8% 5% 24% 43% 16% 4	540
October	1st to 10th	Night	11% 6% 28% 35% 17% 2	710
	11th to 20th	Night	14% 10% 40% 29% 6%	720
	21st to end	Night	20% 12% 33% 26% 8%	792
November	1st to 10th	Night	10% 10% 38% 31% 10% 1	740
	11th to 20th	Night	13% 13% 39% 26% 9%	945
	21st to end	Night	19% 13% 36% 27% 4	950
December	1st to 10th	Night	17% 12% 39% 26% 5% 1	950
	11th to 20th	Night	18% 11% 41% 26% 5%	950
	21st to end	Night	19% 17% 37% 23% 3	1045

Page generated at 2024-06-29 21:08:52. Version ac07

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