Automata Internet Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Automata Internet Observatory clear sky chart from 2005-11-05 to 2017-09-10.

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
74%
15778
37%
46719
30%
15734
80%
15734
62%
20823

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 15thNight
62%
716
29%
2496
27%
716
70%
716
44%
1159
January16th to endNight
58%
768
36%
2339
26%
768
70%
768
47%
1162
February1st to 15thNight
65%
700
34%
2108
31%
699
72%
699
50%
1034
February16th to endNight
59%
632
32%
1895
30%
632
66%
632
43%
991
March1st to 15thNight
63%
720
31%
2160
27%
720
72%
720
55%
1019
March16th to endNight
67%
768
32%
2011
23%
768
74%
768
57%
1039
April1st to 15thNight
59%
719
33%
1799
15%
719
68%
719
60%
923
April16th to endNight
65%
720
36%
1800
18%
720
71%
720
71%
855
May1st to 15thNight
72%
598
36%
1678
23%
598
77%
598
76%
694
May16th to endNight
64%
561
36%
1685
24%
561
72%
561
72%
661
June1st to 15thNight
82%
467
36%
1547
31%
467
87%
467
80%
534
June16th to endNight
94%
360
43%
1440
51%
360
96%
360
86%
399
July1st to 15thNight
95%
340
37%
1360
44%
340
95%
340
69%
438
July16th to endNight
92%
600
36%
1623
30%
561
93%
561
68%
709
August1st to 15thNight
95%
717
39%
1790
26%
713
95%
713
86%
776
August16th to endNight
95%
764
46%
1910
31%
764
95%
764
83%
847
September1st to 15thNight
95%
700
44%
1782
35%
700
95%
700
82%
785
September16th to endNight
87%
656
46%
1815
41%
656
93%
656
85%
719
October1st to 15thNight
79%
660
40%
1820
35%
660
85%
660
67%
832
October16th to endNight
79%
704
43%
2150
42%
704
86%
704
67%
886
November1st to 15thNight
77%
700
37%
2275
37%
700
84%
700
62%
936
November16th to endNight
75%
720
39%
2340
37%
720
82%
720
58%
997
December1st to 15thNight
65%
720
34%
2340
30%
720
73%
720
46%
1124
December16th to endNight
56%
768
32%
2556
26%
768
67%
768
40%
1304

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
111212336%74%
47893
Night
111212346%74%
46914
TransparencyDay
12%27%16%27%32%
47583
Night
13%37%17%28%30%
46724
SeeingDay
28%25%36%20%5%
5871
Night
2217%35%33%8%
15789

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 15thDay
2213323346%65%
1441
16th to endDay
3414422338%60%
1881
February1st to 15thDay
132322335%7%65%
1751
16th to endDay
2213424447%60%
1579
March1st to 15thDay
11112135%7%9%63%
1800
16th to endDay
1212145%6%9%64%
2209
April1st to 15thDay
1212213336%71%
2149
16th to endDay
111247%77%
2160
May1st to 15thDay
1112237%77%
2271
16th to endDay
111112225%79%
2429
June1st to 15thDay
11235%83%
2409
16th to endDay
112388%
2520
July1st to 15thDay
11111223478%
2520
16th to endDay
21112235%77%
2425
August1st to 15thDay
11111386%
2160
16th to endDay
1223482%
2292
September1st to 15thDay
111122382%
2064
16th to endDay
1222384%
1815
October1st to 15thDay
11112345%75%
1807
16th to endDay
11111345%79%
1722
November1st to 15thDay
1111222335%74%
1584
16th to endDay
2212213347%68%
1620
December1st to 15thDay
221222346%10%60%
1620
16th to endDay
331341345%6%60%
1665
January1st to 15thNight
231431335%8%61%
2496
16th to endNight
3312324347%63%
2339
February1st to 15thNight
131321335%7%64%
2101
16th to endNight
23123245%6%7%60%
1895
March1st to 15thNight
121131337%7%66%
2160
16th to endNight
11221346%8%67%
2011
April1st to 15thNight
1212212347%71%
1799
16th to endNight
111111235%79%
1800
May1st to 15thNight
11245%81%
1678
16th to endNight
11123483%
1684
June1st to 15thNight
1135%86%
1547
16th to endNight
111292%
1440
July1st to 15thNight
12213482%
1440
16th to endNight
21121223477%
1736
August1st to 15thNight
1112288%
1800
16th to endNight
1112386%
1910
September1st to 15thNight
11111387%
1782
16th to endNight
112388%
1815
October1st to 15thNight
11113345%77%
1820
16th to endNight
1111223480%
2150
November1st to 15thNight
1111112235%75%
2275
16th to endNight
211213348%71%
2340
December1st to 15thNight
221232345%7%63%
2340
16th to endNight
3323324447%60%
2556

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 15thDay
20%39%18%29%18%
1441
16th to endDay
25%39%19%22%19%
1881
February1st to 15thDay
18%38%22%26%20%
1751
16th to endDay
24%5%9%21%28%10%
1579
March1st to 15thDay
15%312%24%24%19%
1800
16th to endDay
16%5%12%26%23%15%
2209
April1st to 15thDay
16%38%25%31%13%
2149
16th to endDay
8%311%24%32%19%
2160
May1st to 15thDay
8%28%21%32%25%
2271
16th to endDay
10%26%20%41%19%
2432
June1st to 15thDay
6%17%9%30%43%
2409
16th to endDay
5%2418%67%
2520
July1st to 15thDay
10%138%18%58%
2371
16th to endDay
11%25%14%26%39%
2275
August1st to 15thDay
6%128%22%59%
2146
16th to endDay
7%327%28%50%
2292
September1st to 15thDay
8%148%26%50%
2064
16th to endDay
7%138%32%47%
1815
October1st to 15thDay
12%36%15%30%32%
1807
16th to endDay
9%27%13%29%37%
1722
November1st to 15thDay
14%27%15%34%25%
1584
16th to endDay
17%27%19%27%24%
1620
December1st to 15thDay
19%312%23%25%16%
1620
16th to endDay
24%6%11%23%21%12%
1665
January1st to 15thNight
21%38%19%27%19%
2496
16th to endNight
21%410%18%23%22%
2339
February1st to 15thNight
19%310%17%25%22%
2112
16th to endNight
22%5%9%20%27%13%
1895
March1st to 15thNight
16%311%23%24%20%
2160
16th to endNight
15%6%12%23%28%14%
2011
April1st to 15thNight
16%210%29%25%15%
1799
16th to endNight
9%310%26%32%18%
1800
May1st to 15thNight
6%19%23%35%22%
1679
16th to endNight
6%37%23%39%19%
1685
June1st to 15thNight
326%16%32%39%
1547
16th to endNight
236%22%63%
1440
July1st to 15thNight
7%139%15%62%
1360
16th to endNight
11%25%11%27%40%
1623
August1st to 15thNight
5%27%26%57%
1790
16th to endNight
6%18%30%51%
1910
September1st to 15thNight
6%138%29%51%
1782
16th to endNight
438%36%46%
1815
October1st to 15thNight
10%46%13%33%31%
1820
16th to endNight
10%25%12%31%37%
2150
November1st to 15thNight
13%16%17%33%28%
2275
16th to endNight
13%38%21%26%27%
2340
December1st to 15thNight
20%5%10%18%27%18%
2340
16th to endNight
24%5%11%20%23%15%
2556

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 15thDay
10%15%27%28%14%2
69
16th to endDay
6%14%34%24%16%3
281
February1st to 15thDay
215%28%30%19%3
266
16th to endDay
8%16%30%30%10%3
238
March1st to 15thDay
318%27%29%19%2
270
16th to endDay
315%30%32%16%
288
April1st to 15thDay
419%34%23%14%3
269
16th to endDay
220%36%27%10%2
270
May1st to 15thDay
112%30%34%15%5%
288
16th to endDay
310%32%31%16%4
330
June1st to 15thDay
8%26%41%15%6%
315
16th to endDay
1227%39%20%9%
315
July1st to 15thDay
20%44%22%10%
305
16th to endDay
212%46%25%12%
327
August1st to 15thDay
217%49%21%8%
315
16th to endDay
112%44%28%11%
332
September1st to 15thDay
2213%44%31%5%
294
16th to endDay
1419%41%28%5%
255
October1st to 15thDay
110%26%37%21%2
255
16th to endDay
1326%29%35%3
234
November1st to 15thDay
15%13%30%34%15%
90
16th to endDay
46%30%35%23%
90
December1st to 15thDay
1425%34%28%5%
90
16th to endDay
11%11%24%31%17%2
85
January1st to 15thNight
4322%40%20%7%
720
16th to endNight
4327%36%23%4
768
February1st to 15thNight
2322%40%25%6%
704
16th to endNight
4427%35%21%5%
632
March1st to 15thNight
2327%38%24%5%
720
16th to endNight
424%40%25%4
768
April1st to 15thNight
1430%34%24%4
719
16th to endNight
15%26%36%22%6%
720
May1st to 15thNight
321%45%25%4
599
16th to endNight
427%33%30%3
563
June1st to 15thNight
115%48%31%3
467
16th to endNight
448%41%4
360
July1st to 15thNight
126%62%8%
340
16th to endNight
1127%57%12%
600
August1st to 15thNight
1227%55%13%
717
16th to endNight
1121%56%18%
764
September1st to 15thNight
225%54%16%
700
16th to endNight
9%29%47%12%
656
October1st to 15thNight
1114%40%33%8%
660
16th to endNight
1114%32%35%14%
704
November1st to 15thNight
116%38%32%9%
700
16th to endNight
2215%38%30%10%
720
December1st to 15thNight
3321%40%26%5%
720
16th to endNight
4428%36%21%4
768
Page generated at 2017-09-11 16:35:26. Version ac04

Copyright 2017 A. Danko


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