Valle Grande Entrance Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Valle Grande Entrance Station clear sky chart from 2005-11-06 to 2024-11-01.

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	3 5% 2 6% 4 5% 5% 4 7% 7% 52%	100917
	Night	3 5% 2 5% 4 4 4 4 6% 7% 56%	98280
Transparency	Day	26% 5% 9% 22% 25% 13%	100677
	Night	25% 4 8% 22% 27% 15%	98109
Seeing	Day	12% 18% 29% 26% 13% 3	15103
	Night	9% 12% 26% 33% 18% 2	25219

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	1 4 2 8% 4 4 5% 4 5% 7% 57%	2826
	11th to 20th	Day	1 4 2 4 2 3 4 4 7% 7% 63%	2860
	21st to end	Day	2 11% 3 6% 5% 5% 4 4 5% 6% 49%	3146
February	1st to 10th	Day	1 5% 4 8% 5% 3 3 4 5% 8% 54%	1710
	11th to 20th	Day	2 5% 3 8% 4 4 5% 3 6% 7% 54%	1834
	21st to end	Day	1 8% 3 6% 4 3 4 4 5% 7% 55%	1570
March	1st to 10th	Day	1 8% 3 5% 3 3 4 3 5% 7% 57%	3343
	11th to 20th	Day	3 16% 3 7% 5% 4 5% 3 6% 6% 42%	3490
	21st to end	Day	2 7% 2 7% 5% 4 5% 4 7% 6% 51%	3917
April	1st to 10th	Day	2 4 2 5% 4 4 5% 4 6% 7% 58%	2280
	11th to 20th	Day	3 5% 2 5% 5% 3 4 4 6% 6% 57%	2251
	21st to end	Day	3 5% 2 5% 3 5% 3 5% 6% 7% 56%	2280
May	1st to 10th	Day	2 3 1 3 3 3 4 4 5% 6% 65%	3800
	11th to 20th	Day	5% 5% 2 6% 5% 6% 6% 4 6% 7% 47%	3986
	21st to end	Day	3 3 1 4 3 3 3 3 5% 6% 67%	4825
June	1st to 10th	Day	2 3 1 4 4 4 4 5% 8% 8% 57%	2660
	11th to 20th	Day	2 2 1 4 3 3 3 4 6% 6% 65%	2660
	21st to end	Day	5% 4 2 6% 4 5% 5% 4 7% 8% 49%	2660
July	1st to 10th	Day	3 4 2 5% 4 5% 6% 5% 8% 8% 49%	4336
	11th to 20th	Day	2 3 2 6% 6% 7% 11% 10% 11% 9% 34%	4110
	21st to end	Day	4 5% 3 9% 8% 8% 9% 8% 10% 10% 27%	4454
August	1st to 10th	Day	4 4 2 8% 8% 8% 10% 8% 9% 10% 29%	4045
	11th to 20th	Day	3 4 2 6% 5% 6% 6% 5% 8% 11% 43%	3726
	21st to end	Day	5% 4 2 8% 5% 7% 8% 6% 10% 11% 32%	4180
September	1st to 10th	Day	6% 5% 2 6% 5% 5% 6% 5% 7% 8% 44%	2280
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 7% 7% 51%	2280
	21st to end	Day	5% 3 1 4 3 3 3 3 5% 7% 64%	2048
October	1st to 10th	Day	8% 4 2 5% 5% 4 4 4 5% 5% 54%	1900
	11th to 20th	Day	5% 3 1 4 3 1 3 2 3 4 71%	1900
	21st to end	Day	4 4 1 4 2 3 2 2 3 4 69%	2090
November	1st to 10th	Day	2 3 1 3 3 3 3 3 4 6% 69%	1824
	11th to 20th	Day	1 3 1 3 2 2 4 3 5% 7% 67%	1710
	21st to end	Day	4 6% 2 4 3 4 3 3 5% 5% 62%	1696
December	1st to 10th	Day	2 4 2 4 3 3 4 3 6% 6% 62%	1520
	11th to 20th	Day	2 5% 2 7% 5% 5% 4 5% 5% 7% 53%	1926
	21st to end	Day	2 7% 2 5% 3 3 4 3 5% 7% 61%	2794
January	1st to 10th	Night	1 5% 3 7% 4 5% 5% 4 5% 6% 56%	4157
	11th to 20th	Night	1 3 1 5% 3 4 5% 4 6% 6% 62%	4110
	21st to end	Night	2 5% 2 6% 5% 5% 5% 4 7% 8% 51%	4521
February	1st to 10th	Night	1 6% 2 5% 3 3 3 3 5% 6% 62%	2470
	11th to 20th	Night	2 6% 2 5% 4 4 3 4 6% 6% 57%	2233
	21st to end	Night	2 7% 2 4 3 3 3 4 5% 6% 62%	1884
March	1st to 10th	Night	1 5% 2 4 3 3 3 3 4 6% 66%	3524
	11th to 20th	Night	6% 14% 3 5% 4 3 4 3 6% 6% 45%	3490
	21st to end	Night	1 5% 2 6% 5% 5% 4 4 5% 6% 57%	3733
April	1st to 10th	Night	2 4 2 5% 4 3 3 4 6% 7% 60%	1900
	11th to 20th	Night	5% 5% 2 5% 4 3 4 2 4 7% 60%	1877
	21st to end	Night	3 4 1 4 3 3 3 3 4 7% 63%	1900
May	1st to 10th	Night	3 7% 2 4 4 3 3 3 5% 6% 60%	3170
	11th to 20th	Night	7% 9% 2 6% 4 4 4 3 5% 6% 49%	2910
	21st to end	Night	3 2 1 3 2 3 3 3 5% 5% 70%	2762
June	1st to 10th	Night	2 4 2 4 4 5% 5% 4 7% 9% 54%	1520
	11th to 20th	Night	4 3 1 3 2 2 3 4 5% 7% 66%	1520
	21st to end	Night	6% 5% 2 6% 5% 4 5% 5% 5% 8% 49%	1520
July	1st to 10th	Night	3 4 2 6% 6% 5% 6% 5% 7% 6% 49%	2627
	11th to 20th	Night	3 4 3 8% 5% 5% 7% 7% 10% 12% 35%	2860
	21st to end	Night	7% 7% 2 7% 5% 5% 6% 5% 10% 10% 35%	3109
August	1st to 10th	Night	3 5% 3 9% 7% 8% 9% 7% 10% 12% 28%	2894
	11th to 20th	Night	4 4 2 6% 5% 6% 7% 5% 10% 13% 38%	3113
	21st to end	Night	4 5% 3 8% 7% 8% 8% 7% 10% 10% 30%	3487
September	1st to 10th	Night	5% 5% 3 6% 5% 5% 5% 3 6% 9% 49%	1900
	11th to 20th	Night	6% 3 2 5% 4 3 4 4 6% 7% 57%	1900
	21st to end	Night	5% 3 1 4 2 4 3 3 4 6% 65%	2128
October	1st to 10th	Night	7% 5% 2 4 3 3 3 3 4 5% 60%	2280
	11th to 20th	Night	5% 3 1 2 2 2 3 2 3 4 75%	2280
	21st to end	Night	4 3 1 3 3 2 3 3 4 5% 70%	2508
November	1st to 10th	Night	2 2 1 2 2 3 3 2 4 5% 75%	2240
	11th to 20th	Night	2 1 4 2 3 3 3 5% 6% 73%	2470
	21st to end	Night	4 6% 1 4 3 3 3 4 5% 5% 62%	2479
December	1st to 10th	Night	2 4 2 4 3 3 4 4 5% 7% 63%	2660
	11th to 20th	Night	3 5% 1 4 4 4 5% 4 7% 8% 54%	3271
	21st to end	Night	3 6% 3 6% 3 3 3 2 4 6% 61%	4873

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	26% 3 6% 29% 31% 6%	2827
	11th to 20th	Day	17% 1 11% 34% 32% 4	2860
	21st to end	Day	34% 2 6% 27% 26% 5%	3146
February	1st to 10th	Day	27% 3 9% 23% 26% 11%	1710
	11th to 20th	Day	26% 5% 5% 26% 26% 12%	1844
	21st to end	Day	25% 3 4 19% 32% 17%	1570
March	1st to 10th	Day	23% 2 3 19% 42% 11%	3343
	11th to 20th	Day	40% 2 3 26% 23% 6%	3490
	21st to end	Day	28% 2 4 28% 30% 9%	3917
April	1st to 10th	Day	21% 4 6% 22% 31% 17%	2280
	11th to 20th	Day	24% 3 4 20% 32% 17%	2254
	21st to end	Day	22% 4 6% 24% 32% 12%	2280
May	1st to 10th	Day	19% 2 5% 18% 37% 20%	3800
	11th to 20th	Day	34% 3 6% 20% 25% 12%	3989
	21st to end	Day	17% 2 4 13% 27% 36%	4825
June	1st to 10th	Day	20% 4 9% 20% 28% 20%	2660
	11th to 20th	Day	17% 2 4 15% 26% 35%	2660
	21st to end	Day	28% 4 8% 19% 23% 19%	2660
July	1st to 10th	Day	25% 8% 12% 14% 17% 24%	4269
	11th to 20th	Day	31% 12% 18% 28% 7% 4	4041
	21st to end	Day	35% 13% 22% 20% 6% 3	4314
August	1st to 10th	Day	36% 12% 21% 17% 9% 5%	4031
	11th to 20th	Day	26% 8% 16% 24% 17% 8%	3762
	21st to end	Day	33% 11% 18% 21% 15% 3	4179
September	1st to 10th	Day	30% 6% 10% 24% 20% 9%	2280
	11th to 20th	Day	25% 5% 10% 19% 28% 14%	2280
	21st to end	Day	18% 3 6% 26% 34% 13%	2048
October	1st to 10th	Day	29% 3 7% 21% 24% 16%	1900
	11th to 20th	Day	17% 2 3 16% 38% 24%	1900
	21st to end	Day	18% 2 6% 21% 38% 15%	2090
November	1st to 10th	Day	15% 2 5% 25% 38% 15%	1824
	11th to 20th	Day	14% 3 6% 28% 38% 11%	1710
	21st to end	Day	22% 2 4 23% 34% 15%	1696
December	1st to 10th	Day	19% 4 9% 33% 23% 11%	1520
	11th to 20th	Day	27% 4 8% 22% 29% 9%	1924
	21st to end	Day	23% 3 7% 21% 30% 17%	2794
January	1st to 10th	Night	26% 2 6% 24% 31% 10%	4157
	11th to 20th	Night	18% 2 7% 33% 31% 9%	4110
	21st to end	Night	28% 2 7% 26% 29% 7%	4521
February	1st to 10th	Night	22% 2 8% 25% 29% 14%	2470
	11th to 20th	Night	23% 3 6% 25% 28% 15%	2233
	21st to end	Night	20% 3 4 19% 35% 20%	1884
March	1st to 10th	Night	20% 2 2 17% 46% 13%	3524
	11th to 20th	Night	38% 1 3 25% 26% 7%	3490
	21st to end	Night	27% 2 3 27% 31% 9%	3733
April	1st to 10th	Night	21% 3 5% 22% 31% 16%	1900
	11th to 20th	Night	23% 3 5% 19% 30% 20%	1877
	21st to end	Night	20% 3 7% 21% 36% 12%	1900
May	1st to 10th	Night	25% 2 4 13% 32% 23%	3170
	11th to 20th	Night	36% 2 6% 21% 20% 14%	2911
	21st to end	Night	17% 1 5% 11% 24% 42%	2762
June	1st to 10th	Night	24% 4 10% 20% 21% 21%	1520
	11th to 20th	Night	18% 3 4 14% 24% 38%	1520
	21st to end	Night	30% 5% 9% 15% 18% 23%	1520
July	1st to 10th	Night	29% 8% 10% 13% 13% 27%	2585
	11th to 20th	Night	31% 10% 22% 26% 6% 5%	2806
	21st to end	Night	36% 8% 21% 27% 8% 1	3011
August	1st to 10th	Night	38% 13% 19% 16% 9% 6%	2885
	11th to 20th	Night	28% 8% 20% 17% 15% 11%	3143
	21st to end	Night	38% 10% 19% 17% 12% 4	3487
September	1st to 10th	Night	28% 5% 13% 23% 20% 10%	1900
	11th to 20th	Night	24% 5% 10% 16% 26% 19%	1900
	21st to end	Night	19% 4 6% 19% 34% 18%	2128
October	1st to 10th	Night	26% 3 7% 18% 26% 20%	2280
	11th to 20th	Night	14% 2 3 17% 35% 29%	2280
	21st to end	Night	15% 3 4 22% 37% 18%	2508
November	1st to 10th	Night	12% 2 3 26% 42% 16%	2240
	11th to 20th	Night	11% 3 5% 26% 40% 14%	2470
	21st to end	Night	22% 2 5% 21% 33% 18%	2479
December	1st to 10th	Night	19% 3 8% 32% 28% 10%	2660
	11th to 20th	Night	24% 3 9% 22% 29% 13%	3272
	21st to end	Night	25% 2 6% 21% 29% 17%	4873

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	13% 24% 33% 24% 6%	270
	11th to 20th	Day	24% 21% 27% 23% 4	270
	21st to end	Day	7% 22% 39% 20% 11% 1	297
February	1st to 10th	Day	14% 27% 33% 21% 4	270
	11th to 20th	Day	16% 30% 36% 16% 3	270
	21st to end	Day	25% 29% 29% 14% 3	225
March	1st to 10th	Day	15% 33% 36% 13% 4 1	393
	11th to 20th	Day	20% 30% 29% 15% 5% 1	460
	21st to end	Day	24% 34% 30% 8% 4	506
April	1st to 10th	Day	17% 33% 32% 13% 4 1	460
	11th to 20th	Day	19% 36% 33% 10% 2	452
	21st to end	Day	17% 33% 36% 12% 2	460
May	1st to 10th	Day	13% 30% 43% 12% 3	463
	11th to 20th	Day	11% 24% 36% 20% 7% 2	497
	21st to end	Day	12% 21% 31% 26% 9% 1	734
June	1st to 10th	Day	5% 11% 32% 33% 17% 1	680
	11th to 20th	Day	6% 15% 30% 29% 18% 2	680
	21st to end	Day	8% 12% 28% 30% 18% 4	680
July	1st to 10th	Day	7% 5% 23% 32% 29% 5%	618
	11th to 20th	Day	7% 3 12% 36% 35% 8%	484
	21st to end	Day	6% 2 11% 39% 33% 8%	531
August	1st to 10th	Day	8% 4 14% 37% 29% 8%	487
	11th to 20th	Day	8% 3 23% 41% 20% 5%	477
	21st to end	Day	7% 4 20% 39% 24% 6%	539
September	1st to 10th	Day	6% 7% 21% 39% 21% 6%	490
	11th to 20th	Day	8% 8% 32% 35% 13% 4	490
	21st to end	Day	8% 14% 29% 29% 15% 6%	343
October	1st to 10th	Day	10% 19% 26% 25% 15% 5%	300
	11th to 20th	Day	15% 16% 29% 24% 12% 4	300
	21st to end	Day	15% 16% 28% 27% 10% 2	330
November	1st to 10th	Day	14% 21% 34% 25% 6%	270
	11th to 20th	Day	8% 18% 36% 26% 12% 1	270
	21st to end	Day	13% 27% 29% 20% 11%	270
December	1st to 10th	Day	14% 23% 31% 24% 8%	270
	11th to 20th	Day	13% 24% 34% 24% 4 1	270
	21st to end	Day	23% 25% 32% 18% 1 1	297
January	1st to 10th	Night	7% 15% 28% 33% 15% 3	794
	11th to 20th	Night	10% 15% 28% 32% 12% 3	760
	21st to end	Night	8% 14% 32% 30% 13% 3	836
February	1st to 10th	Night	9% 16% 33% 30% 10% 1	760
	11th to 20th	Night	11% 16% 39% 26% 8% 1	744
	21st to end	Night	13% 23% 33% 27% 4	628
March	1st to 10th	Night	9% 22% 33% 27% 8% 1	760
	11th to 20th	Night	11% 18% 27% 31% 12% 1	760
	21st to end	Night	13% 20% 33% 27% 8%	779
April	1st to 10th	Night	12% 22% 39% 23% 4	570
	11th to 20th	Night	12% 25% 28% 28% 8%	563
	21st to end	Night	10% 23% 32% 27% 7%	570
May	1st to 10th	Night	9% 18% 34% 31% 8%	570
	11th to 20th	Night	10% 14% 29% 32% 15% 1	561
	21st to end	Night	7% 15% 32% 33% 13%	617
June	1st to 10th	Night	4 9% 26% 41% 19% 1	570
	11th to 20th	Night	6% 9% 29% 40% 15% 1	570
	21st to end	Night	7% 7% 23% 34% 27% 2	570
July	1st to 10th	Night	6% 2 18% 36% 35% 3	555
	11th to 20th	Night	4 2 7% 38% 44% 5%	552
	21st to end	Night	6% 1 6% 29% 50% 8%	624
August	1st to 10th	Night	5% 3 10% 29% 42% 10%	567
	11th to 20th	Night	8% 1 10% 41% 36% 4	564
	21st to end	Night	4 2 10% 38% 40% 6%	627
September	1st to 10th	Night	8% 2 14% 41% 30% 5%	570
	11th to 20th	Night	6% 3 20% 40% 26% 4	570
	21st to end	Night	7% 5% 21% 41% 24% 2	651
October	1st to 10th	Night	8% 9% 27% 39% 16% 2	760
	11th to 20th	Night	7% 9% 28% 38% 15% 3	760
	21st to end	Night	10% 11% 26% 33% 16% 5%	836
November	1st to 10th	Night	5% 10% 25% 37% 20% 2	756
	11th to 20th	Night	4 12% 29% 34% 17% 3	950
	21st to end	Night	12% 14% 24% 29% 17% 3	950
December	1st to 10th	Night	9% 15% 31% 33% 11% 1	950
	11th to 20th	Night	12% 16% 29% 30% 12% 1	950
	21st to end	Night	14% 16% 31% 30% 8% 1	1045

Page generated at 2024-10-29 09:20:45. Version ac07

Copyright © 2024 Attilla Danko.