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 2024-01-14.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
61%
23676
25%
74809
23%
23630
64%
23630
34%
42797

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
53%
756
16%
2551
17%
756
56%
756
23%
1658
January11th to 20thNight
57%
734
20%
2384
18%
734
62%
734
26%
1464
January21st to endNight
55%
792
23%
2574
24%
792
57%
792
24%
1643
February1st to 10thNight
57%
720
25%
2340
25%
720
62%
720
29%
1390
February11th to 20thNight
52%
700
23%
2189
21%
700
58%
700
28%
1340
February21st to endNight
56%
592
24%
1776
22%
592
60%
592
32%
1066
March1st to 10thNight
47%
720
16%
2021
13%
720
51%
720
23%
1383
March11th to 20thNight
51%
720
23%
1980
20%
720
54%
720
28%
1319
March21st to endNight
51%
792
18%
2142
12%
792
55%
792
29%
1396
April1st to 10thNight
53%
720
20%
1800
13%
720
55%
720
33%
1177
April11th to 20thNight
51%
711
25%
1779
12%
711
55%
711
38%
1115
April21st to endNight
63%
720
26%
1800
14%
720
66%
720
47%
1035
May1st to 10thNight
60%
653
25%
1733
16%
653
62%
653
42%
1000
May11th to 20thNight
58%
470
22%
1533
19%
470
59%
470
35%
831
May21st to endNight
56%
388
22%
1552
23%
388
60%
388
28%
812
June1st to 10thNight
65%
360
23%
1440
27%
360
69%
360
35%
688
June11th to 20thNight
75%
360
32%
1440
38%
360
79%
360
49%
579
June21st to endNight
70%
360
30%
1440
38%
360
74%
360
50%
565
July1st to 10thNight
74%
350
27%
1400
36%
350
75%
350
54%
533
July11th to 20thNight
73%
492
30%
1536
30%
492
73%
492
54%
694
July21st to endNight
64%
591
28%
1674
25%
558
66%
558
47%
819
August1st to 10thNight
59%
537
25%
1602
21%
534
59%
534
38%
851
August11th to 20thNight
71%
648
30%
1716
20%
648
72%
648
55%
885
August21st to endNight
70%
792
30%
1980
19%
792
71%
792
56%
1072
September1st to 10thNight
77%
720
37%
1800
27%
720
77%
720
59%
943
September11th to 20thNight
63%
720
32%
1800
24%
720
65%
720
48%
1032
September21st to endNight
76%
720
37%
2043
35%
720
80%
720
59%
969
October1st to 10thNight
72%
720
29%
2160
30%
720
76%
720
50%
1063
October11th to 20thNight
67%
720
32%
2160
35%
720
71%
720
43%
1151
October21st to endNight
68%
792
35%
2376
36%
792
72%
792
45%
1232
November1st to 10thNight
66%
740
28%
2261
28%
740
70%
740
37%
1274
November11th to 20thNight
64%
760
26%
2470
27%
760
67%
760
33%
1395
November21st to endNight
65%
760
27%
2615
28%
760
70%
760
35%
1385
December1st to 10thNight
56%
760
21%
2660
21%
760
62%
760
26%
1600
December11th to 20thNight
51%
760
16%
3241
19%
759
55%
759
16%
2273
December21st to endNight
45%
826
12%
4841
16%
817
52%
817
13%
3165

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 ForecastData
Points
Cloud CoverDay
8%6%24323347%57%
74706
Night
10%7%35%424447%49%
75062
TransparencyDay
26%5%9%19%24%17%
74425
Night
31%6%11%18%20%15%
74865
SeeingDay
10%9%25%32%19%5%
14256
Night
13%313%35%30%6%
23695

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
19%7%36%5%245%6%8%35%
1609
11th to 20thDay
14%5%25%5%25%346%48%
1648
21st to endDay
15%7%35%5%3445%8%41%
1782
February1st to 10thDay
16%7%35%42435%6%46%
1620
11th to 20thDay
13%8%45%42445%8%44%
1660
21st to endDay
15%6%25%5%33346%48%
1480
March1st to 10thDay
16%7%46%5%25%46%8%36%
1934
11th to 20thDay
16%7%36%5%35%5%5%7%37%
1980
21st to endDay
13%6%25%435%5%6%8%43%
2213
April1st to 10thDay
13%7%35%5%3445%7%43%
2160
11th to 20thDay
10%6%2432335%6%56%
2129
21st to endDay
6%42442345%9%58%
2160
May1st to 10thDay
5%6%2431445%7%60%
2222
11th to 20thDay
6%5%24223349%59%
2359
21st to endDay
6%7%24323347%57%
2723
June1st to 10thDay
5%6%24324348%59%
2520
11th to 20thDay
2313312346%73%
2520
21st to endDay
3423322235%71%
2520
July1st to 10thDay
1433213347%70%
2520
11th to 20thDay
1424223347%68%
2368
21st to endDay
1323213347%72%
2546
August1st to 10thDay
26%25%323236%66%
2328
11th to 20thDay
1323212436%72%
2183
21st to endDay
1424222245%72%
2376
September1st to 10thDay
232321222476%
2160
11th to 20thDay
36%24323348%62%
2160
21st to endDay
3312212236%73%
1914
October1st to 10thDay
4323313336%70%
1800
11th to 20thDay
6%423323347%63%
1800
21st to endDay
7%5%24322437%61%
1980
November1st to 10thDay
8%5%243245%5%9%53%
1817
11th to 20thDay
10%7%36%433447%50%
1710
21st to endDay
12%5%2433346%7%53%
1563
December1st to 10thDay
14%7%35%4345%5%6%46%
1520
11th to 20thDay
24%9%46%5%2445%5%31%
1928
21st to endDay
17%12%36%5%3445%8%34%
2794
January1st to 10thNight
16%8%36%5%3445%8%38%
2551
11th to 20thNight
13%7%35%5%245%5%7%43%
2384
21st to endNight
16%7%35%4245%5%6%44%
2574
February1st to 10thNight
17%6%2432335%5%49%
2340
11th to 20thNight
12%6%35%435%45%7%45%
2187
21st to endNight
13%6%34423437%50%
1776
March1st to 10thNight
18%8%36%5%34446%40%
2021
11th to 20thNight
16%7%36%5%3435%7%40%
1980
21st to endNight
14%8%25%434345%47%
2142
April1st to 10thNight
11%9%35%5%2446%8%45%
1800
11th to 20thNight
11%6%33323446%53%
1779
21st to endNight
6%42433445%8%57%
1800
May1st to 10thNight
6%8%35%423347%55%
1733
11th to 20thNight
5%10%47%324448%48%
1532
21st to endNight
6%15%34423437%48%
1552
June1st to 10thNight
7%8%25%41445%7%53%
1440
11th to 20thNight
2434323347%65%
1440
21st to endNight
28%46%31333463%
1440
July1st to 10thNight
19%45%323237%60%
1440
11th to 20thNight
25%5%6%423447%57%
1588
21st to endNight
28%6%8%5%2447%8%47%
1773
August1st to 10thNight
313%6%7%5%33447%44%
1611
11th to 20thNight
17%37%42446%9%53%
1716
21st to endNight
18%5%7%423447%54%
1980
September1st to 10thNight
16%44323436%64%
1800
11th to 20thNight
49%5%8%424347%51%
1800
21st to endNight
35%2332235%6%67%
2043
October1st to 10thNight
5%425%3235%36%63%
2160
11th to 20thNight
7%6%26%423346%57%
2160
21st to endNight
7%5%2442335%6%58%
2376
November1st to 10thNight
9%6%2433445%7%53%
2261
11th to 20thNight
10%7%35%33335%7%51%
2470
21st to endNight
10%41442435%7%56%
2615
December1st to 10thNight
14%6%35%434346%47%
2660
11th to 20thNight
27%10%35%32345%6%32%
3276
21st to endNight
18%9%36%6%35%5%47%34%
4862

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
44%8%13%20%10%4
1609
11th to 20thDay
37%6%12%16%18%12%
1648
21st to endDay
42%7%10%13%21%7%
1782
February1st to 10thDay
39%49%19%20%8%
1620
11th to 20thDay
39%6%10%17%22%7%
1669
21st to endDay
38%5%10%23%18%6%
1480
March1st to 10thDay
45%6%11%19%15%4
1934
11th to 20thDay
44%6%10%20%16%4
1980
21st to endDay
37%8%15%19%17%4
2213
April1st to 10thDay
39%6%14%19%19%4
2160
11th to 20thDay
29%5%15%24%22%5%
2132
21st to endDay
24%5%15%27%25%5%
2160
May1st to 10thDay
22%5%11%26%29%7%
2222
11th to 20thDay
21%5%10%29%27%8%
2362
21st to endDay
25%7%13%29%23%4
2724
June1st to 10thDay
23%6%11%26%25%10%
2520
11th to 20thDay
12%49%21%36%18%
2520
21st to endDay
14%35%14%31%34%
2520
July1st to 10thDay
12%27%9%23%47%
2451
11th to 20thDay
13%37%11%21%44%
2297
21st to endDay
10%25%10%28%44%
2405
August1st to 10thDay
18%35%13%28%32%
2312
11th to 20thDay
10%35%12%33%36%
2183
21st to endDay
12%46%13%32%33%
2376
September1st to 10thDay
12%2410%30%42%
2160
11th to 20thDay
19%5%7%21%30%18%
2160
21st to endDay
12%37%21%33%24%
1914
October1st to 10thDay
17%49%17%29%24%
1800
11th to 20thDay
20%5%10%18%22%24%
1800
21st to endDay
23%49%20%23%20%
1980
November1st to 10thDay
28%6%11%24%20%12%
1817
11th to 20thDay
33%6%10%21%23%6%
1710
21st to endDay
30%5%12%18%27%9%
1563
December1st to 10thDay
37%8%11%19%17%9%
1520
11th to 20thDay
54%5%9%14%13%4
1928
21st to endDay
47%8%13%18%11%3
2794
January1st to 10thNight
42%8%13%20%12%5%
2551
11th to 20thNight
39%6%13%15%14%13%
2384
21st to endNight
41%7%11%13%18%10%
2574
February1st to 10thNight
37%49%19%19%11%
2340
11th to 20thNight
37%6%10%18%21%8%
2189
21st to endNight
34%5%13%26%18%4
1776
March1st to 10thNight
45%6%13%16%15%5%
2021
11th to 20thNight
43%5%8%22%17%6%
1980
21st to endNight
38%7%13%20%17%5%
2142
April1st to 10thNight
35%7%16%20%17%5%
1800
11th to 20thNight
31%7%13%23%19%8%
1779
21st to endNight
23%6%13%30%22%6%
1800
May1st to 10thNight
29%410%22%25%11%
1733
11th to 20thNight
27%7%12%22%24%7%
1533
21st to endNight
29%7%14%23%22%4
1552
June1st to 10thNight
25%5%11%24%24%10%
1440
11th to 20thNight
15%5%9%19%30%22%
1440
21st to endNight
15%37%16%28%30%
1440
July1st to 10thNight
15%28%10%22%43%
1400
11th to 20thNight
18%38%12%20%40%
1536
21st to endNight
23%38%11%23%33%
1674
August1st to 10thNight
29%37%13%21%26%
1602
11th to 20thNight
19%46%14%25%33%
1716
21st to endNight
21%38%13%27%29%
1980
September1st to 10thNight
17%449%23%43%
1800
11th to 20thNight
25%49%19%25%18%
1800
21st to endNight
14%5%7%20%29%25%
2043
October1st to 10thNight
19%5%10%17%24%25%
2160
11th to 20thNight
25%5%8%18%20%24%
2160
21st to endNight
23%5%8%21%22%21%
2376
November1st to 10thNight
29%6%12%23%16%14%
2261
11th to 20thNight
32%6%12%23%20%8%
2470
21st to endNight
28%5%10%21%24%11%
2615
December1st to 10thNight
37%7%11%17%17%12%
2660
11th to 20thNight
53%5%10%13%15%3
3276
21st to endNight
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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
24%12%26%21%13%4
270
11th to 20thDay
19%7%22%28%20%3
350
21st to endDay
15%6%24%31%20%4
374
February1st to 10thDay
18%9%21%25%22%4
340
11th to 20thDay
19%13%28%25%14%2
373
21st to endDay
14%13%27%34%12%1
346
March1st to 10thDay
20%15%30%23%10%3
420
11th to 20thDay
19%17%23%24%13%4
420
21st to endDay
16%14%34%23%12%1
462
April1st to 10thDay
18%15%31%24%10%3
420
11th to 20thDay
15%17%32%25%8%4
412
21st to endDay
8%19%30%28%10%5%
420
May1st to 10thDay
10%14%32%30%12%3
423
11th to 20thDay
12%13%30%29%13%2
448
21st to endDay
13%11%27%31%13%5%
485
June1st to 10thDay
7%11%29%32%17%4
450
11th to 20thDay
310%28%40%15%4
450
21st to endDay
47%26%39%19%5%
450
July1st to 10thDay
45%20%47%19%5%
446
11th to 20thDay
1220%44%29%4
444
21st to endDay
3120%44%25%8%
487
August1st to 10thDay
6%5%21%40%21%6%
447
11th to 20thDay
3220%44%22%9%
437
21st to endDay
4320%39%27%7%
495
September1st to 10thDay
4416%42%26%9%
450
11th to 20thDay
5%8%24%36%20%7%
450
21st to endDay
47%21%33%28%7%
450
October1st to 10thDay
48%26%32%21%9%
450
11th to 20thDay
8%8%18%32%26%8%
450
21st to endDay
8%7%24%31%21%9%
495
November1st to 10thDay
8%10%22%25%27%8%
413
11th to 20thDay
7%9%15%34%26%10%
270
21st to endDay
10%5%23%30%28%3
201
December1st to 10thDay
16%12%20%22%23%7%
180
11th to 20thDay
16%11%20%26%23%5%
180
21st to endDay
22%10%25%21%19%3
198
January1st to 10thNight
19%5%13%34%22%7%
760
11th to 20thNight
16%5%12%36%26%5%
734
21st to endNight
20%312%37%23%5%
792
February1st to 10thNight
18%413%36%25%4
720
11th to 20thNight
13%5%19%36%23%5%
704
21st to endNight
15%7%16%40%19%3
592
March1st to 10thNight
20%6%18%31%23%3
720
11th to 20thNight
20%5%13%34%24%4
720
21st to endNight
17%7%17%38%19%2
792
April1st to 10thNight
14%5%17%40%22%2
720
11th to 20thNight
14%6%21%32%22%5%
711
21st to endNight
8%5%19%39%23%5%
720
May1st to 10thNight
11%416%40%25%5%
653
11th to 20thNight
13%212%37%31%5%
470
21st to endNight
15%5%14%35%26%5%
389
June1st to 10thNight
11%212%42%30%3
360
11th to 20thNight
6%111%49%31%2
360
21st to endNight
6%410%36%41%3
360
July1st to 10thNight
7%25%32%51%3
350
11th to 20thNight
6%436%42%12%
492
21st to endNight
8%18%25%47%12%
591
August1st to 10thNight
15%18%28%39%9%
537
11th to 20thNight
8%19%34%41%8%
648
21st to endNight
7%18%34%42%9%
792
September1st to 10thNight
7%17%32%43%10%
720
11th to 20thNight
10%212%33%35%7%
720
21st to endNight
5%210%30%41%12%
720
October1st to 10thNight
8%29%37%36%8%
720
11th to 20thNight
10%210%31%38%9%
720
21st to endNight
10%310%33%32%12%
792
November1st to 10thNight
10%312%33%33%9%
740
11th to 20thNight
13%211%36%31%7%
760
21st to endNight
12%214%38%27%6%
760
December1st to 10thNight
17%414%36%24%5%
760
11th to 20thNight
25%412%35%20%5%
760
21st to endNight
21%5%21%32%19%2
836
Page generated at 2024-01-11 01:22:40. Version ac07

Copyright 2024 Attilla Danko


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