Rustic Valley Observator
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rustic Valley Observator clear sky chart from 2005-11-05 to 2017-09-20.

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
73%
16128
40%
46997
31%
16088
82%
16088
68%
19982

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
72%
718
35%
2327
31%
716
81%
716
55%
1025
January16th to endNight
65%
768
39%
2358
31%
768
78%
768
52%
1103
February1st to 15thNight
66%
699
39%
2106
31%
697
80%
697
59%
935
February16th to endNight
60%
632
38%
1895
34%
632
71%
632
56%
880
March1st to 15thNight
62%
720
37%
2133
29%
720
76%
720
65%
907
March16th to endNight
64%
768
39%
2084
25%
768
77%
768
66%
944
April1st to 15thNight
56%
719
39%
1799
16%
719
70%
719
67%
856
April16th to endNight
60%
711
43%
1791
18%
711
72%
711
78%
789
May1st to 15thNight
69%
539
43%
1619
27%
539
78%
539
80%
605
May16th to endNight
65%
561
40%
1685
26%
561
74%
561
81%
618
June1st to 15thNight
72%
540
36%
1620
27%
540
78%
540
85%
591
June16th to endNight
82%
540
38%
1620
31%
540
86%
540
83%
606
July1st to 15thNight
90%
510
32%
1530
28%
510
91%
510
72%
622
July16th to endNight
90%
564
37%
1593
31%
531
91%
531
62%
709
August1st to 15thNight
92%
708
38%
1782
24%
705
93%
705
81%
796
August16th to endNight
92%
764
44%
1910
31%
764
92%
764
76%
891
September1st to 15thNight
91%
720
40%
1896
32%
720
93%
720
77%
838
September16th to endNight
86%
675
49%
1869
42%
675
92%
675
87%
729
October1st to 15thNight
73%
660
46%
1815
35%
660
83%
660
79%
759
October16th to endNight
80%
704
46%
2114
42%
704
88%
704
77%
822
November1st to 15thNight
77%
700
40%
2275
36%
700
88%
700
73%
857
November16th to endNight
76%
720
44%
2340
43%
720
84%
720
66%
925
December1st to 15thNight
70%
720
38%
2340
33%
720
80%
720
54%
1037
December16th to endNight
62%
768
37%
2496
31%
768
72%
768
49%
1138

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
111112235%78%
47831
Night
11111223479%
47198
TransparencyDay
9%25%12%25%44%
47526
Night
9%35%13%26%41%
47004
SeeingDay
29%24%37%19%5%
5833
Night
1318%34%33%7%
16138

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
212312336%71%
1611
16th to endDay
322313345%69%
1865
February1st to 15thDay
221112237%73%
1751
16th to endDay
211221335%8%67%
1579
March1st to 15thDay
111112237%75%
1825
16th to endDay
11112336%77%
2137
April1st to 15thDay
111212236%74%
2149
16th to endDay
1115%85%
2166
May1st to 15thDay
11122485%
2331
16th to endDay
11122387%
2429
June1st to 15thDay
111387%
2340
16th to endDay
1111289%
2340
July1st to 15thDay
111112246%73%
2340
16th to endDay
2112223348%68%
2467
August1st to 15thDay
111112245%78%
2166
16th to endDay
11121233477%
2292
September1st to 15thDay
1121234477%
2063
16th to endDay
11112287%
1860
October1st to 15thDay
111123481%
1815
16th to endDay
11233482%
1753
November1st to 15thDay
11121222480%
1584
16th to endDay
11112246%77%
1620
December1st to 15thDay
31121246%8%66%
1620
16th to endDay
321123346%69%
1728
January1st to 15thNight
11222335%5%71%
2327
16th to endNight
32122334469%
2358
February1st to 15thNight
1111222245%73%
2101
16th to endNight
32221336%7%66%
1895
March1st to 15thNight
11212346%75%
2133
16th to endNight
11111347%75%
2084
April1st to 15thNight
1111224479%
1799
16th to endNight
11111486%
1791
May1st to 15thNight
1111389%
1619
16th to endNight
12389%
1684
June1st to 15thNight
111290%
1620
16th to endNight
111191%
1620
July1st to 15thNight
111123481%
1620
16th to endNight
111223345%72%
1701
August1st to 15thNight
11123482%
1791
16th to endNight
1111122382%
1910
September1st to 15thNight
1111123483%
1896
16th to endNight
111291%
1869
October1st to 15thNight
11125%82%
1815
16th to endNight
111123484%
2114
November1st to 15thNight
111222382%
2275
16th to endNight
11112235%78%
2340
December1st to 15thNight
212213447%69%
2340
16th to endNight
4212213336%69%
2496

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
15%37%18%26%28%
1612
16th to endDay
17%46%16%26%28%
1865
February1st to 15thDay
13%28%14%30%30%
1751
16th to endDay
14%49%19%28%23%
1579
March1st to 15thDay
9%25%16%29%35%
1825
16th to endDay
9%36%18%32%30%
2137
April1st to 15thDay
11%25%12%34%33%
2149
16th to endDay
5%1314%30%44%
2166
May1st to 15thDay
5%139%30%47%
2331
16th to endDay
42311%27%50%
2432
June1st to 15thDay
4128%17%65%
2340
16th to endDay
5%149%78%
2340
July1st to 15thDay
11%239%18%52%
2201
16th to endDay
14%47%15%23%33%
2312
August1st to 15thDay
8%448%21%51%
2151
16th to endDay
10%35%7%21%50%
2292
September1st to 15thDay
9%35%10%19%51%
2063
16th to endDay
5%115%22%62%
1860
October1st to 15thDay
8%239%27%49%
1815
16th to endDay
6%36%9%22%52%
1753
November1st to 15thDay
9%25%12%28%42%
1584
16th to endDay
9%26%14%27%38%
1620
December1st to 15thDay
14%49%21%22%27%
1620
16th to endDay
16%49%22%25%20%
1728
January1st to 15thNight
14%47%17%25%30%
2327
16th to endNight
17%47%17%21%31%
2358
February1st to 15thNight
13%36%16%25%34%
2112
16th to endNight
15%49%20%26%24%
1895
March1st to 15thNight
10%37%16%31%30%
2133
16th to endNight
9%48%16%32%29%
2084
April1st to 15thNight
9%37%17%35%27%
1799
16th to endNight
5%25%14%32%40%
1791
May1st to 15thNight
32314%32%43%
1620
16th to endNight
31413%37%39%
1685
June1st to 15thNight
31211%20%60%
1620
16th to endNight
415%8%79%
1620
July1st to 15thNight
7%338%19%57%
1530
16th to endNight
12%45%15%28%34%
1593
August1st to 15thNight
5%2410%24%52%
1782
16th to endNight
8%228%23%54%
1910
September1st to 15thNight
7%2411%20%53%
1896
16th to endNight
316%24%63%
1869
October1st to 15thNight
7%149%33%43%
1815
16th to endNight
5%25%10%21%54%
2114
November1st to 15thNight
7%25%11%31%41%
2275
16th to endNight
10%2415%28%38%
2340
December1st to 15thNight
14%5%8%19%23%29%
2340
16th to endNight
16%411%19%24%22%
2496

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%10%18%50%11%
90
16th to endDay
5%14%28%36%12%2
233
February1st to 15thDay
214%31%31%18%1
266
16th to endDay
5%20%31%29%11%
238
March1st to 15thDay
317%28%32%15%3
270
16th to endDay
117%34%30%13%2
288
April1st to 15thDay
5%21%31%25%11%4
269
16th to endDay
220%38%24%11%1
270
May1st to 15thDay
113%30%38%10%4
288
16th to endDay
11%32%36%13%5%
330
June1st to 15thDay
26%27%40%19%4
315
16th to endDay
2223%35%26%9%
315
July1st to 15thDay
12%45%28%11%
305
16th to endDay
27%41%33%14%
327
August1st to 15thDay
112%47%27%10%
315
16th to endDay
119%44%28%13%
332
September1st to 15thDay
1122%48%20%5%
315
16th to endDay
15%21%44%21%5%
272
October1st to 15thDay
10%29%44%12%1
255
16th to endDay
26%21%37%27%4
174
November1st to 15thDay
10%16%31%33%8%
90
16th to endDay
26%36%24%27%2
90
December1st to 15thDay
310%15%35%31%4
90
16th to endDay
38%32%39%16%
96
January1st to 15thNight
1319%40%24%10%
720
16th to endNight
3323%35%26%6%
768
February1st to 15thNight
1323%37%27%6%
704
16th to endNight
3429%34%21%5%
632
March1st to 15thNight
1429%35%24%5%
720
16th to endNight
16%26%35%24%6%
768
April1st to 15thNight
18%32%33%18%4
719
16th to endNight
6%31%32%22%5%
711
May1st to 15thNight
5%23%45%21%3
540
16th to endNight
6%26%37%25%3
563
June1st to 15thNight
124%44%28%1
540
16th to endNight
115%43%37%2
540
July1st to 15thNight
1438%51%4
510
16th to endNight
2332%55%6%
564
August1st to 15thNight
1430%53%11%
708
16th to endNight
2219%60%15%
764
September1st to 15thNight
15%30%52%10%
720
16th to endNight
110%30%44%11%
675
October1st to 15thNight
122%33%34%6%
660
16th to endNight
214%30%36%14%
704
November1st to 15thNight
1119%32%35%10%
700
16th to endNight
2216%33%30%13%
720
December1st to 15thNight
4219%35%28%9%
720
16th to endNight
5%6%23%35%22%6%
768
Page generated at 2017-09-21 04:18:12. Version ac04

Copyright 2017 A. Danko


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