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 2024-12-02.

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	11% 7% 3 6% 4 4 4 3 5% 7% 45%	101241
	Night	11% 7% 3 6% 4 4 4 3 5% 6% 48%	98467
Transparency	Day	37% 4 13% 26% 17% 2	104892
	Night	36% 4 12% 26% 19% 3	102956
Seeing	Day	14% 11% 29% 28% 15% 3	15745
	Night	14% 10% 33% 32% 11% 1	25614

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	10% 7% 2 7% 4 4 5% 4 7% 8% 41%	4120
	11th to 20th	Day	5% 3 2 5% 4 4 4 4 7% 10% 54%	4120
	21st to end	Day	6% 4 1 5% 4 5% 6% 5% 8% 10% 45%	4465
August	1st to 10th	Day	5% 4 2 6% 3 4 4 4 6% 9% 53%	4104
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 8% 47%	4041
	21st to end	Day	5% 4 2 5% 3 3 4 3 6% 8% 57%	4262
September	1st to 10th	Day	12% 4 2 4 3 3 3 3 5% 7% 54%	2280
	11th to 20th	Day	8% 5% 2 5% 5% 4 4 4 5% 7% 50%	2104
	21st to end	Day	9% 4 2 6% 3 3 4 4 5% 6% 54%	2080
October	1st to 10th	Day	11% 5% 2 5% 3 3 3 2 6% 7% 53%	1900
	11th to 20th	Day	12% 6% 2 4 3 3 3 2 4 5% 57%	1900
	21st to end	Day	15% 6% 3 6% 3 3 4 2 4 6% 48%	2090
November	1st to 10th	Day	10% 6% 2 5% 3 3 4 3 4 6% 54%	1958
	11th to 20th	Day	14% 6% 2 4 4 3 3 3 4 7% 51%	1735
	21st to end	Day	14% 8% 2 7% 3 4 3 3 3 5% 49%	1600
December	1st to 10th	Day	9% 9% 3 5% 6% 4 3 3 5% 8% 45%	1528
	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	10% 6% 3 7% 4 4 4 3 5% 7% 48%	2850
	11th to 20th	Night	3 3 1 4 3 3 5% 4 6% 9% 60%	2850
	21st to end	Night	5% 3 2 4 4 4 6% 5% 7% 11% 49%	3098
August	1st to 10th	Night	2 1 1 3 3 4 5% 5% 6% 10% 61%	2836
	11th to 20th	Night	10% 7% 2 5% 3 3 4 3 4 6% 52%	2798
	21st to end	Night	3 3 1 5% 4 3 4 3 5% 8% 60%	3383
September	1st to 10th	Night	9% 4 2 5% 3 3 3 3 4 5% 57%	1900
	11th to 20th	Night	9% 5% 2 4 3 3 4 4 6% 7% 54%	2073
	21st to end	Night	6% 4 2 5% 4 4 3 3 5% 5% 59%	2090
October	1st to 10th	Night	10% 4 1 5% 3 3 3 3 4 5% 58%	2270
	11th to 20th	Night	12% 4 2 5% 3 2 3 3 4 5% 58%	2280
	21st to end	Night	15% 7% 2 5% 3 3 3 2 4 4 52%	2508
November	1st to 10th	Night	9% 5% 2 4 3 3 3 2 4 5% 61%	2340
	11th to 20th	Night	10% 7% 2 4 3 3 3 3 5% 7% 54%	2658
	21st to end	Night	14% 7% 2 4 3 3 3 3 3 5% 53%	2800
December	1st to 10th	Night	11% 8% 3 5% 4 4 3 4 5% 6% 46%	2687
	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	40% 4 14% 21% 17% 3	4056
	11th to 20th	Day	26% 4 14% 36% 18% 2	4051
	21st to end	Day	31% 4 18% 33% 12% 1	4325
August	1st to 10th	Day	28% 5% 14% 30% 21% 2	4090
	11th to 20th	Day	36% 4 18% 26% 15% 1	4080
	21st to end	Day	26% 4 15% 36% 14% 4	4261
September	1st to 10th	Day	31% 5% 12% 26% 20% 6%	2280
	11th to 20th	Day	32% 6% 11% 26% 23% 2	2104
	21st to end	Day	30% 4 10% 29% 24% 3	2080
October	1st to 10th	Day	19% 2 7% 23% 41% 8%	3160
	11th to 20th	Day	20% 2 5% 25% 39% 9%	3140
	21st to end	Day	33% 2 10% 25% 26% 3	3428
November	1st to 10th	Day	33% 4 12% 28% 19% 5%	1958
	11th to 20th	Day	36% 3 10% 26% 21% 4	1735
	21st to end	Day	40% 3 10% 28% 19% 1	1600
December	1st to 10th	Day	38% 4 14% 30% 13% 1	1528
	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	21% 5% 14% 34% 23% 4	1540
July	1st to 10th	Night	36% 3 14% 24% 18% 4	2805
	11th to 20th	Night	20% 4 14% 39% 21% 3	2796
	21st to end	Night	29% 4 21% 32% 13% 1	2999
August	1st to 10th	Night	19% 3 21% 29% 22% 6%	2826
	11th to 20th	Night	34% 3 12% 29% 20% 2	2825
	21st to end	Night	24% 3 12% 39% 17% 4	3383
September	1st to 10th	Night	29% 4 11% 27% 21% 8%	1900
	11th to 20th	Night	28% 5% 10% 27% 25% 5%	2073
	21st to end	Night	28% 4 7% 28% 29% 5%	2090
October	1st to 10th	Night	18% 3 5% 21% 44% 8%	3790
	11th to 20th	Night	22% 2 5% 26% 31% 14%	3779
	21st to end	Night	34% 2 7% 30% 25% 3	4120
November	1st to 10th	Night	28% 3 12% 27% 24% 6%	2340
	11th to 20th	Night	32% 3 9% 27% 24% 5%	2658
	21st to end	Night	36% 3 10% 30% 19% 3	2800
December	1st to 10th	Night	38% 4 13% 27% 16% 1	2687
	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% 5% 15% 32% 27% 10%	671
	11th to 20th	Day	5% 3 19% 41% 26% 7%	668
	21st to end	Day	8% 3 16% 38% 27% 8%	739
August	1st to 10th	Day	7% 3 18% 40% 29% 4	676
	11th to 20th	Day	8% 3 19% 38% 25% 6%	665
	21st to end	Day	9% 2 16% 32% 33% 9%	595
September	1st to 10th	Day	12% 3 16% 39% 24% 6%	490
	11th to 20th	Day	6% 2 22% 42% 22% 6%	314
	21st to end	Day	10% 6% 30% 32% 17% 4	300
October	1st to 10th	Day	12% 7% 33% 26% 16% 6%	300
	11th to 20th	Day	11% 17% 43% 23% 6% 1	300
	21st to end	Day	21% 17% 37% 21% 4 1	330
November	1st to 10th	Day	16% 17% 34% 26% 7% 1	300
	11th to 20th	Day	20% 17% 32% 21% 8% 1	300
	21st to end	Day	20% 17% 34% 22% 6%	300
December	1st to 10th	Day	10% 18% 40% 26% 3 3	273
	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 13% 45% 28% 3	555
	11th to 20th	Night	3 2 17% 47% 28% 3	552
	21st to end	Night	7% 2 14% 45% 30% 2	624
August	1st to 10th	Night	3 2 16% 47% 31% 1	567
	11th to 20th	Night	8% 3 13% 46% 27% 2	564
	21st to end	Night	6% 2 15% 41% 34% 2	627
September	1st to 10th	Night	11% 3 20% 40% 22% 4	570
	11th to 20th	Night	10% 2 21% 39% 23% 4	570
	21st to end	Night	8% 5% 24% 42% 17% 4	570
October	1st to 10th	Night	11% 6% 28% 35% 18% 2	750
	11th to 20th	Night	13% 10% 40% 30% 7%	760
	21st to end	Night	20% 12% 33% 27% 8%	836
November	1st to 10th	Night	11% 10% 37% 31% 10% 1	780
	11th to 20th	Night	14% 14% 38% 25% 8%	995
	21st to end	Night	19% 13% 36% 27% 5%	1000
December	1st to 10th	Night	17% 11% 39% 26% 5% 1	960
	11th to 20th	Night	18% 11% 41% 26% 5%	950
	21st to end	Night	19% 17% 37% 23% 3	1045

Page generated at 2024-11-29 09:43:11. Version ac07

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