Barking Spider Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barking Spider Observatory clear sky chart from 2005-11-06 to 2024-11-25.

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	7% 6% 2 5% 3 3 3 3 4 6% 58%	105206
	Night	10% 9% 4 7% 3 3 3 3 4 6% 49%	103020
Transparency	Day	25% 5% 9% 18% 23% 21%	104964
	Night	32% 6% 10% 17% 19% 16%	102852
Seeing	Day	10% 9% 25% 32% 19% 5%	15466
	Night	13% 4 13% 35% 29% 6%	24804

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	18% 8% 3 6% 4 3 4 4 6% 7% 37%	2681
	11th to 20th	Day	18% 9% 4 10% 6% 4 4 3 4 5% 33%	2860
	21st to end	Day	22% 10% 3 8% 5% 4 4 4 5% 7% 28%	3146
February	1st to 10th	Day	16% 8% 3 5% 4 3 3 3 5% 6% 45%	1710
	11th to 20th	Day	13% 9% 3 6% 4 3 3 3 5% 7% 42%	1754
	21st to end	Day	14% 7% 2 6% 5% 3 4 3 4 6% 47%	1570
March	1st to 10th	Day	13% 11% 4 10% 6% 5% 6% 4 5% 6% 28%	3374
	11th to 20th	Day	11% 5% 2 5% 3 3 3 3 4 7% 53%	3490
	21st to end	Day	12% 8% 2 7% 5% 5% 6% 5% 8% 8% 34%	3885
April	1st to 10th	Day	13% 8% 2 6% 5% 4 3 3 5% 7% 44%	2280
	11th to 20th	Day	10% 6% 1 5% 3 3 4 3 5% 6% 55%	2249
	21st to end	Day	6% 5% 2 4 3 3 3 3 5% 9% 57%	2280
May	1st to 10th	Day	6% 4 1 3 2 1 2 2 3 5% 71%	3914
	11th to 20th	Day	4 4 1 3 2 2 2 2 3 6% 71%	4181
	21st to end	Day	3 8% 2 4 2 2 2 2 3 5% 65%	4813
June	1st to 10th	Day	5% 6% 1 4 3 3 3 3 5% 7% 59%	2660
	11th to 20th	Day	2 3 1 3 2 2 2 2 4 6% 72%	2660
	21st to end	Day	3 4 2 4 2 2 2 2 3 5% 71%	2660
July	1st to 10th	Day	1 3 1 3 2 1 2 1 2 4 80%	4420
	11th to 20th	Day	1 3 2 4 2 3 3 2 3 6% 72%	4151
	21st to end	Day	5% 2 3 2 2 3 2 4 6% 71%	4455
August	1st to 10th	Day	2 4 2 6% 3 3 4 3 5% 8% 61%	4091
	11th to 20th	Day	3 2 4 2 2 3 2 3 5% 73%	3821
	21st to end	Day	1 4 2 4 2 3 3 2 4 5% 70%	4180
September	1st to 10th	Day	2 3 2 3 2 2 2 1 3 5% 76%	2280
	11th to 20th	Day	3 7% 3 4 3 3 3 2 4 7% 61%	2280
	21st to end	Day	3 3 1 3 2 2 2 2 3 6% 74%	2019
October	1st to 10th	Day	2 2 1 3 2 2 3 2 4 6% 72%	3180
	11th to 20th	Day	4 5% 2 4 2 3 3 2 3 6% 64%	3161
	21st to end	Day	5% 6% 1 4 3 3 3 3 5% 8% 59%	3448
November	1st to 10th	Day	8% 5% 2 4 2 3 4 3 5% 8% 55%	1914
	11th to 20th	Day	10% 7% 3 7% 4 3 3 3 4 7% 48%	1800
	21st to end	Day	12% 6% 2 4 3 3 3 3 6% 6% 52%	1597
December	1st to 10th	Day	13% 8% 3 6% 3 3 4 4 5% 6% 45%	1520
	11th to 20th	Day	24% 10% 3 7% 4 4 3 4 5% 5% 31%	1928
	21st to end	Day	17% 12% 3 7% 4 4 4 4 5% 8% 34%	2794
January	1st to 10th	Night	14% 8% 2 6% 3 4 4 3 5% 7% 44%	4251
	11th to 20th	Night	19% 10% 3 8% 5% 5% 5% 3 5% 6% 31%	4110
	21st to end	Night	22% 13% 4 7% 4 4 3 3 4 5% 30%	4521
February	1st to 10th	Night	17% 7% 2 4 3 3 3 3 5% 5% 48%	2470
	11th to 20th	Night	13% 7% 3 6% 4 4 4 3 5% 7% 43%	2313
	21st to end	Night	13% 7% 2 5% 3 4 3 3 4 7% 51%	1884
March	1st to 10th	Night	17% 13% 4 9% 5% 4 4 3 4 5% 32%	3495
	11th to 20th	Night	12% 7% 5% 6% 3 3 3 2 4 5% 49%	3490
	21st to end	Night	15% 14% 3 7% 5% 4 4 3 4 6% 35%	3767
April	1st to 10th	Night	11% 9% 2 6% 4 3 3 4 5% 7% 46%	1900
	11th to 20th	Night	11% 7% 3 4 3 3 3 3 4 6% 53%	1879
	21st to end	Night	6% 5% 1 4 3 4 4 3 5% 9% 56%	1900
May	1st to 10th	Night	5% 7% 2 4 2 2 2 2 3 5% 66%	3057
	11th to 20th	Night	3 8% 4 12% 5% 3 3 3 3 5% 51%	2716
	21st to end	Night	4 14% 5% 4 2 3 2 2 3 4 56%	2762
June	1st to 10th	Night	7% 8% 2 6% 3 3 3 3 5% 7% 52%	1520
	11th to 20th	Night	2 4 3 4 3 3 3 3 4 7% 65%	1520
	21st to end	Night	2 8% 4 6% 2 2 2 2 3 5% 63%	1520
July	1st to 10th	Night	1 5% 3 6% 2 2 2 1 3 4 72%	2540
	11th to 20th	Night	1 6% 8% 9% 3 2 3 3 3 6% 56%	2814
	21st to end	Night	1 18% 8% 8% 3 2 3 3 5% 6% 43%	3109
August	1st to 10th	Night	3 8% 6% 24% 6% 3 4 4 3 6% 32%	2848
	11th to 20th	Night	1 10% 6% 7% 2 2 3 2 4 6% 57%	3023
	21st to end	Night	3 10% 4 11% 3 2 3 2 3 5% 54%	3498
September	1st to 10th	Night	1 6% 4 4 3 2 4 3 3 6% 63%	1900
	11th to 20th	Night	4 10% 5% 9% 3 3 4 2 4 7% 50%	1900
	21st to end	Night	2 5% 2 4 3 2 2 2 4 6% 66%	2158
October	1st to 10th	Night	3 3 2 4 2 2 2 3 4 6% 69%	3800
	11th to 20th	Night	4 13% 6% 7% 3 3 2 2 3 4 52%	3777
	21st to end	Night	7% 4 2 5% 3 3 4 3 5% 6% 57%	4121
November	1st to 10th	Night	9% 6% 2 4 3 4 3 3 5% 7% 53%	2384
	11th to 20th	Night	10% 7% 2 5% 3 4 3 3 5% 8% 50%	2600
	21st to end	Night	11% 5% 1 5% 3 3 3 3 5% 7% 55%	2675
December	1st to 10th	Night	14% 7% 3 6% 3 4 3 3 4 6% 47%	2660
	11th to 20th	Night	27% 10% 2 5% 3 3 3 3 5% 6% 31%	3276
	21st to end	Night	17% 9% 3 7% 5% 5% 5% 4 4 7% 34%	4862

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	42% 9% 13% 26% 7% 3	2681
	11th to 20th	Day	51% 7% 11% 13% 11% 7%	2860
	21st to end	Day	53% 8% 10% 13% 12% 4	3146
February	1st to 10th	Day	40% 5% 9% 19% 20% 8%	1710
	11th to 20th	Day	39% 7% 10% 17% 20% 7%	1763
	21st to end	Day	37% 6% 10% 24% 18% 6%	1570
March	1st to 10th	Day	51% 10% 10% 13% 13% 3	3374
	11th to 20th	Day	29% 6% 12% 28% 14% 11%	3490
	21st to end	Day	39% 12% 18% 18% 10% 2	3885
April	1st to 10th	Day	38% 6% 14% 20% 19% 4	2280
	11th to 20th	Day	29% 6% 15% 24% 22% 5%	2252
	21st to end	Day	23% 5% 15% 27% 25% 5%	2280
May	1st to 10th	Day	16% 3 11% 31% 24% 15%	3914
	11th to 20th	Day	12% 4 7% 25% 40% 12%	4184
	21st to end	Day	16% 7% 9% 31% 33% 4	4814
June	1st to 10th	Day	22% 6% 11% 26% 26% 10%	2660
	11th to 20th	Day	11% 4 8% 21% 37% 18%	2660
	21st to end	Day	13% 3 4 13% 31% 36%	2660
July	1st to 10th	Day	7% 1 4 6% 13% 69%	4351
	11th to 20th	Day	13% 2 4 8% 13% 61%	4080
	21st to end	Day	11% 2 3 6% 27% 50%	4315
August	1st to 10th	Day	16% 2 4 10% 26% 42%	4076
	11th to 20th	Day	10% 2 4 9% 41% 34%	3859
	21st to end	Day	14% 3 4 11% 32% 35%	4179
September	1st to 10th	Day	12% 2 3 9% 30% 43%	2280
	11th to 20th	Day	20% 5% 7% 21% 30% 17%	2280
	21st to end	Day	12% 3 7% 20% 33% 25%	2019
October	1st to 10th	Day	14% 3 5% 11% 27% 40%	3180
	11th to 20th	Day	20% 4 7% 22% 27% 20%	3161
	21st to end	Day	23% 3 7% 20% 30% 15%	3448
November	1st to 10th	Day	27% 5% 11% 24% 21% 12%	1914
	11th to 20th	Day	33% 6% 11% 22% 22% 6%	1800
	21st to end	Day	31% 5% 12% 18% 26% 9%	1597
December	1st to 10th	Day	37% 8% 11% 19% 17% 9%	1520
	11th to 20th	Day	54% 5% 9% 14% 13% 4	1928
	21st to end	Day	47% 8% 13% 18% 11% 3	2794
January	1st to 10th	Night	38% 9% 20% 21% 9% 3	4251
	11th to 20th	Night	52% 9% 13% 11% 9% 7%	4110
	21st to end	Night	55% 7% 9% 12% 11% 6%	4521
February	1st to 10th	Night	38% 4 10% 19% 18% 10%	2470
	11th to 20th	Night	38% 6% 11% 17% 20% 7%	2315
	21st to end	Night	34% 5% 13% 27% 17% 4	1884
March	1st to 10th	Night	49% 11% 12% 12% 13% 3	3495
	11th to 20th	Night	31% 8% 12% 22% 16% 11%	3490
	21st to end	Night	43% 13% 15% 16% 10% 3	3767
April	1st to 10th	Night	34% 7% 15% 21% 17% 5%	1900
	11th to 20th	Night	30% 7% 13% 25% 18% 7%	1879
	21st to end	Night	23% 7% 13% 29% 23% 5%	1900
May	1st to 10th	Night	20% 6% 11% 25% 24% 13%	3057
	11th to 20th	Night	16% 10% 10% 24% 27% 13%	2717
	21st to end	Night	18% 10% 11% 30% 28% 3	2762
June	1st to 10th	Night	24% 6% 11% 25% 24% 10%	1520
	11th to 20th	Night	15% 5% 8% 19% 31% 21%	1520
	21st to end	Night	15% 3 7% 15% 28% 32%	1520
July	1st to 10th	Night	11% 1 5% 8% 12% 64%	2500
	11th to 20th	Night	24% 2 5% 8% 12% 49%	2762
	21st to end	Night	34% 2 5% 9% 20% 31%	3011
August	1st to 10th	Night	40% 2 5% 12% 19% 22%	2839
	11th to 20th	Night	22% 2 4 10% 34% 27%	3051
	21st to end	Night	27% 2 6% 10% 27% 28%	3498
September	1st to 10th	Night	18% 4 4 8% 23% 43%	1900
	11th to 20th	Night	26% 4 9% 19% 25% 17%	1900
	21st to end	Night	15% 4 6% 19% 29% 26%	2158
October	1st to 10th	Night	15% 3 6% 11% 21% 45%	3800
	11th to 20th	Night	33% 4 7% 16% 19% 22%	3777
	21st to end	Night	25% 4 6% 21% 24% 20%	4121
November	1st to 10th	Night	28% 6% 11% 23% 18% 14%	2384
	11th to 20th	Night	31% 6% 12% 24% 20% 8%	2600
	21st to end	Night	29% 5% 10% 21% 23% 11%	2675
December	1st to 10th	Night	37% 7% 11% 17% 17% 12%	2660
	11th to 20th	Night	53% 5% 10% 13% 15% 3	3276
	21st to end	Night	47% 9% 16% 14% 11% 4	4862

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	24% 12% 26% 21% 13% 4	270
	11th to 20th	Day	19% 8% 22% 29% 19% 3	370
	21st to end	Day	16% 6% 24% 30% 19% 4	407
February	1st to 10th	Day	19% 11% 22% 25% 20% 4	370
	11th to 20th	Day	19% 14% 29% 24% 13% 2	407
	21st to end	Day	13% 14% 27% 34% 11% 2	382
March	1st to 10th	Day	20% 16% 29% 22% 10% 2	460
	11th to 20th	Day	18% 17% 23% 24% 14% 4	460
	21st to end	Day	16% 15% 35% 22% 11% 1	506
April	1st to 10th	Day	17% 14% 31% 24% 10% 4	460
	11th to 20th	Day	15% 16% 31% 25% 10% 4	452
	21st to end	Day	8% 18% 30% 27% 10% 6%	460
May	1st to 10th	Day	10% 14% 32% 30% 12% 2	463
	11th to 20th	Day	11% 12% 29% 31% 14% 2	488
	21st to end	Day	12% 11% 28% 31% 14% 5%	529
June	1st to 10th	Day	7% 11% 30% 32% 16% 4	490
	11th to 20th	Day	3 10% 30% 39% 15% 3	490
	21st to end	Day	3 7% 28% 38% 19% 5%	490
July	1st to 10th	Day	4 4 21% 46% 20% 5%	486
	11th to 20th	Day	1 2 22% 43% 28% 4	484
	21st to end	Day	3 2 21% 42% 24% 8%	531
August	1st to 10th	Day	5% 5% 22% 40% 21% 7%	487
	11th to 20th	Day	4 3 23% 42% 20% 8%	477
	21st to end	Day	4 3 21% 38% 26% 8%	539
September	1st to 10th	Day	4 4 18% 41% 26% 9%	490
	11th to 20th	Day	6% 10% 25% 33% 19% 7%	490
	21st to end	Day	3 7% 22% 33% 28% 7%	490
October	1st to 10th	Day	4 7% 26% 32% 22% 9%	490
	11th to 20th	Day	8% 8% 19% 31% 27% 8%	490
	21st to end	Day	8% 8% 25% 30% 20% 8%	539
November	1st to 10th	Day	8% 11% 22% 25% 26% 8%	450
	11th to 20th	Day	9% 9% 17% 33% 24% 9%	300
	21st to end	Day	13% 5% 23% 29% 27% 3	211
December	1st to 10th	Day	16% 12% 20% 22% 23% 7%	180
	11th to 20th	Day	16% 11% 20% 26% 23% 5%	180
	21st to end	Day	22% 10% 25% 21% 19% 3	198
January	1st to 10th	Night	19% 5% 13% 34% 22% 7%	760
	11th to 20th	Night	16% 5% 12% 36% 26% 5%	760
	21st to end	Night	20% 4 12% 37% 22% 5%	836
February	1st to 10th	Night	19% 4 14% 36% 23% 4	760
	11th to 20th	Night	14% 6% 19% 35% 22% 4	744
	21st to end	Night	14% 7% 16% 41% 19% 3	628
March	1st to 10th	Night	20% 7% 18% 31% 22% 3	760
	11th to 20th	Night	20% 6% 14% 34% 23% 4	760
	21st to end	Night	17% 7% 18% 37% 18% 2	836
April	1st to 10th	Night	14% 5% 18% 40% 22% 2	760
	11th to 20th	Night	14% 7% 20% 33% 22% 5%	751
	21st to end	Night	8% 5% 19% 39% 23% 5%	760
May	1st to 10th	Night	11% 4 16% 40% 24% 4	689
	11th to 20th	Night	12% 2 13% 37% 31% 5%	496
	21st to end	Night	15% 5% 14% 36% 26% 5%	411
June	1st to 10th	Night	11% 2 13% 42% 29% 3	380
	11th to 20th	Night	6% 1 12% 50% 30% 2	380
	21st to end	Night	6% 4 10% 36% 41% 3	380
July	1st to 10th	Night	6% 2 5% 32% 51% 4	370
	11th to 20th	Night	6% 4 37% 41% 11%	521
	21st to end	Night	8% 1 8% 25% 47% 11%	624
August	1st to 10th	Night	14% 1 8% 29% 39% 8%	567
	11th to 20th	Night	8% 1 10% 34% 39% 8%	685
	21st to end	Night	7% 9% 34% 41% 9%	836
September	1st to 10th	Night	7% 1 8% 32% 43% 10%	760
	11th to 20th	Night	11% 3 13% 32% 34% 7%	760
	21st to end	Night	5% 2 10% 31% 41% 12%	760
October	1st to 10th	Night	8% 2 9% 37% 37% 8%	760
	11th to 20th	Night	11% 3 10% 31% 37% 9%	760
	21st to end	Night	9% 3 10% 35% 31% 11%	836
November	1st to 10th	Night	10% 3 13% 32% 33% 8%	780
	11th to 20th	Night	13% 3 12% 36% 29% 7%	800
	21st to end	Night	13% 2 14% 37% 27% 6%	778
December	1st to 10th	Night	17% 4 14% 36% 24% 5%	760
	11th to 20th	Night	25% 4 12% 35% 20% 5%	760
	21st to end	Night	21% 5% 21% 32% 19% 2	836

Page generated at 2024-11-22 05:02:28. Version ac07

Copyright © 2024 Attilla Danko.