Nothing Observing Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nothing Observing Station clear sky chart from 2005-11-05 to 2018-02-13.

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
77%
16366
38%
48775
33%
16328
81%
16328
57%
22570

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
70%
778
34%
2522
33%
776
76%
776
46%
1227
January16th to endNight
69%
832
38%
2704
38%
832
76%
832
47%
1309
February1st to 15thNight
74%
746
37%
2275
35%
746
81%
746
53%
1073
February16th to endNight
67%
632
35%
1895
36%
632
71%
632
47%
971
March1st to 15thNight
69%
720
38%
2032
32%
720
77%
720
56%
983
March16th to endNight
73%
768
37%
2112
30%
768
78%
768
57%
1042
April1st to 15thNight
65%
719
33%
1945
20%
719
72%
719
57%
965
April16th to endNight
69%
579
44%
1659
30%
579
78%
579
70%
696
May1st to 15thNight
76%
539
39%
1619
30%
539
81%
539
67%
673
May16th to endNight
77%
561
39%
1684
30%
561
81%
561
71%
679
June1st to 15thNight
82%
540
35%
1620
31%
540
84%
540
74%
643
June16th to endNight
88%
540
36%
1620
34%
540
89%
540
80%
617
July1st to 15thNight
88%
510
27%
1530
24%
510
88%
510
56%
718
July16th to endNight
82%
564
29%
1593
24%
531
83%
531
44%
838
August1st to 15thNight
88%
539
36%
1611
30%
536
89%
536
59%
745
August16th to endNight
84%
723
38%
1884
30%
723
84%
723
55%
1004
September1st to 15thNight
84%
720
33%
1980
28%
720
85%
720
55%
1003
September16th to endNight
85%
716
47%
1980
39%
716
89%
716
75%
833
October1st to 15thNight
80%
720
41%
2013
34%
720
85%
720
66%
903
October16th to endNight
82%
768
45%
2304
41%
768
87%
768
66%
983
November1st to 15thNight
81%
760
38%
2419
38%
760
85%
760
59%
1052
November16th to endNight
78%
780
43%
2535
44%
780
83%
780
58%
1086
December1st to 15thNight
73%
780
37%
2535
37%
780
78%
780
50%
1186
December16th to endNight
68%
832
38%
2704
37%
832
74%
832
44%
1341

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
3212213345%69%
49262
Night
4212213335%69%
48971
TransparencyDay
16%2412%25%39%
48957
Night
16%2412%25%39%
48777
SeeingDay
5%8%24%35%18%5%
6037
Night
4210%35%37%8%
16377

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
6%22312346%65%
1746
16th to endDay
7%312313335%63%
1872
February1st to 15thDay
5%212222236%67%
1850
16th to endDay
7%314322346%59%
1579
March1st to 15thDay
422213346%68%
1926
16th to endDay
3212223335%69%
2112
April1st to 15thDay
4212223336%67%
2000
16th to endDay
11111235%78%
2301
May1st to 15thDay
111212225%77%
2331
16th to endDay
1111123479%
2429
June1st to 15thDay
1111111384%
2340
16th to endDay
111113383%
2340
July1st to 15thDay
21123245%46%65%
2340
16th to endDay
5%314436%6%7%8%46%
2467
August1st to 15thDay
42133245%6%7%57%
2340
16th to endDay
32332435%6%62%
2315
September1st to 15thDay
4212224447%64%
1980
16th to endDay
21111222379%
1980
October1st to 15thDay
22121223476%
1945
16th to endDay
121212225%76%
1920
November1st to 15thDay
2312212335%72%
1767
16th to endDay
5%21221233470%
1755
December1st to 15thDay
5%31332345%7%60%
1755
16th to endDay
9%21331325%6%60%
1872
January1st to 15thNight
5%314313336%63%
2522
16th to endNight
7%313212335%64%
2704
February1st to 15thNight
4212212335%68%
2264
16th to endNight
7%313413336%60%
1895
March1st to 15thNight
5%213213346%67%
2032
16th to endNight
3213213345%67%
2112
April1st to 15thNight
4113223225%69%
1945
16th to endNight
2111133478%
1659
May1st to 15thNight
21121232478%
1619
16th to endNight
1112133479%
1684
June1st to 15thNight
1111122481%
1620
16th to endNight
11211385%
1620
July1st to 15thNight
1123345%46%65%
1620
16th to endNight
2213435%5%7%11%51%
1701
August1st to 15thNight
21112235%6%7%65%
1620
16th to endNight
42122235%47%62%
1884
September1st to 15thNight
221242335%7%63%
1980
16th to endNight
21111112383%
1980
October1st to 15thNight
3111223476%
2013
16th to endNight
11121223377%
2304
November1st to 15thNight
2112213345%71%
2419
16th to endNight
411221223473%
2535
December1st to 15thNight
6%22323345%65%
2535
16th to endNight
8%313323345%60%
2704

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
21%2414%31%26%
1747
16th to endDay
23%1415%26%27%
1872
February1st to 15thDay
19%1415%29%29%
1850
16th to endDay
24%2416%27%24%
1579
March1st to 15thDay
16%1312%31%34%
1926
16th to endDay
17%2412%32%30%
2112
April1st to 15thDay
17%1212%30%35%
2000
16th to endDay
9%210%29%47%
2301
May1st to 15thDay
11%1310%27%45%
2331
16th to endDay
10%38%24%52%
2432
June1st to 15thDay
8%417%68%
2340
16th to endDay
7%1310%76%
2340
July1st to 15thDay
17%36%11%17%42%
2201
16th to endDay
28%6%9%19%18%17%
2312
August1st to 15thDay
21%46%14%22%30%
2325
16th to endDay
21%36%13%24%30%
2315
September1st to 15thDay
18%26%13%23%34%
1980
16th to endDay
10%115%24%56%
1980
October1st to 15thDay
13%129%24%48%
1945
16th to endDay
12%139%23%49%
1920
November1st to 15thDay
15%1412%31%34%
1767
16th to endDay
17%1311%26%39%
1755
December1st to 15thDay
23%35%18%22%27%
1755
16th to endDay
25%16%18%29%18%
1872
January1st to 15thNight
23%2314%27%29%
2522
16th to endNight
23%1315%25%30%
2704
February1st to 15thNight
19%26%12%26%33%
2275
16th to endNight
25%1413%27%27%
1895
March1st to 15thNight
18%1211%29%35%
2032
16th to endNight
18%1412%31%31%
2112
April1st to 15thNight
18%1310%30%35%
1945
16th to endNight
9%139%27%49%
1659
May1st to 15thNight
11%1210%28%45%
1620
16th to endNight
9%29%26%50%
1685
June1st to 15thNight
8%116%15%66%
1620
16th to endNight
6%310%77%
1620
July1st to 15thNight
15%47%13%14%44%
1530
16th to endNight
23%5%9%21%18%20%
1593
August1st to 15thNight
13%5%5%14%26%34%
1611
16th to endNight
19%45%14%26%29%
1884
September1st to 15thNight
18%35%16%21%33%
1980
16th to endNight
8%115%23%60%
1980
October1st to 15thNight
12%2310%24%46%
2013
16th to endNight
12%138%20%52%
2304
November1st to 15thNight
15%1310%32%36%
2419
16th to endNight
15%1310%27%41%
2535
December1st to 15thNight
21%2415%25%30%
2535
16th to endNight
25%1418%29%19%
2704

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
20%211%37%21%5%
135
16th to endDay
8%7%11%30%29%11%
144
February1st to 15thDay
7%9%27%34%16%5%
293
16th to endDay
12%18%34%23%8%2
238
March1st to 15thDay
6%15%27%33%11%4
270
16th to endDay
5%20%32%27%11%2
288
April1st to 15thDay
10%18%28%24%11%5%
269
16th to endDay
5%28%34%21%7%3
270
May1st to 15thDay
5%14%36%28%10%4
288
16th to endDay
312%37%31%11%3
330
June1st to 15thDay
38%36%35%13%3
315
16th to endDay
1422%45%20%5%
315
July1st to 15thDay
2117%52%21%4
305
16th to endDay
417%48%26%10%
327
August1st to 15thDay
5%114%47%23%7%
315
16th to endDay
4113%43%26%9%
332
September1st to 15thDay
5%226%42%17%5%
315
16th to endDay
46%28%38%18%3
315
October1st to 15thDay
38%35%31%18%2
280
16th to endDay
3313%31%36%11%
144
November1st to 15thDay
25%17%31%37%6%
135
16th to endDay
8%221%32%26%8%
135
December1st to 15thDay
25%17%37%33%4
135
16th to endDay
9%414%32%31%6%
144
January1st to 15thNight
6%212%40%27%10%
780
16th to endNight
9%212%39%28%8%
832
February1st to 15thNight
6%211%40%32%7%
752
16th to endNight
9%212%46%22%5%
632
March1st to 15thNight
5%315%38%31%5%
720
16th to endNight
4312%41%31%6%
768
April1st to 15thNight
4419%36%29%5%
719
16th to endNight
35%19%40%26%5%
579
May1st to 15thNight
2313%40%33%5%
540
16th to endNight
1313%42%34%4
563
June1st to 15thNight
229%42%39%4
540
16th to endNight
17%34%48%7%
540
July1st to 15thNight
1323%60%10%
510
16th to endNight
4216%64%12%
564
August1st to 15thNight
3219%64%9%
539
16th to endNight
5%216%56%18%
723
September1st to 15thNight
35%24%52%13%
720
16th to endNight
317%32%44%11%
716
October1st to 15thNight
3110%41%35%7%
720
16th to endNight
218%33%39%14%
768
November1st to 15thNight
318%43%34%9%
760
16th to endNight
419%36%36%11%
780
December1st to 15thNight
7%110%41%31%7%
780
16th to endNight
10%112%38%27%9%
832
Page generated at 2018-02-13 18:46:01. Version ac04

Copyright 2018 A. Danko


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