Appold Planetarium
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Appold Planetarium 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
36%
16446
16%
48666
10%
16405
42%
16405
21%
33744

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
16%
974
11%
2716
4%
970
22%
970
13%
2120
January16th to endNight
16%
897
8%
2769
3%
897
22%
897
11%
2196
February1st to 15thNight
17%
750
10%
2397
4%
750
24%
750
11%
1839
February16th to endNight
22%
631
14%
1893
6%
631
30%
631
14%
1430
March1st to 15thNight
28%
720
13%
2079
9%
720
32%
720
17%
1530
March16th to endNight
30%
768
18%
2112
10%
768
37%
768
21%
1489
April1st to 15thNight
26%
587
14%
1821
7%
587
35%
587
18%
1260
April16th to endNight
34%
540
19%
1620
7%
540
44%
540
24%
1081
May1st to 15thNight
38%
540
13%
1620
7%
540
45%
540
19%
1173
May16th to endNight
47%
562
16%
1684
11%
561
52%
561
28%
1081
June1st to 15thNight
50%
540
15%
1467
10%
540
55%
540
32%
949
June16th to endNight
53%
540
17%
1440
11%
540
60%
540
33%
916
July1st to 15thNight
62%
510
17%
1360
13%
510
64%
510
38%
813
July16th to endNight
67%
564
19%
1523
15%
531
71%
531
40%
866
August1st to 15thNight
67%
539
21%
1609
16%
536
69%
536
37%
928
August16th to endNight
65%
573
22%
1758
18%
573
69%
573
34%
1027
September1st to 15thNight
57%
669
25%
1929
19%
669
62%
669
35%
1140
September16th to endNight
58%
717
27%
1980
21%
717
61%
717
35%
1197
October1st to 15thNight
47%
720
20%
2059
16%
720
51%
720
27%
1332
October16th to endNight
27%
768
19%
2400
12%
768
37%
768
19%
1639
November1st to 15thNight
35%
760
21%
2471
15%
760
44%
760
23%
1580
November16th to endNight
25%
780
16%
2535
10%
780
32%
780
15%
1832
December1st to 15thNight
20%
780
10%
2535
4%
780
27%
780
12%
1930
December16th to endNight
15%
1017
8%
2889
2%
1017
21%
1017
10%
2396

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
14%8%36%5%35%5%5%7%33%
49361
Night
15%8%36%5%3445%6%35%
48846
Cloud CoverDay
14%8%36%5%35%5%5%7%33%
49371
Night
15%8%36%5%3445%6%36%
48850
TransparencyDay
49%5%12%20%11%1
49060
Night
47%5%11%20%12%1
48666
SeeingDay
16%10%27%23%14%7%
6312
Night
19%9%28%28%13%1
16451

By Month

Percentage Cloud Cover NE (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
20%14%5%7%7%44445%19%
1552
16th to endDay
16%18%7%9%8%345%35%17%
1805
February1st to 15thDay
15%13%5%11%7%5%6%445%21%
1728
16th to endDay
15%12%5%10%7%35%35%5%22%
1580
March1st to 15thDay
18%12%5%8%6%235%5%6%25%
1870
16th to endDay
19%11%47%5%3435%5%29%
2112
April1st to 15thDay
19%10%35%5%35%5%47%29%
2134
16th to endDay
17%8%35%43435%7%37%
2340
May1st to 15thDay
17%8%46%5%35%5%5%7%30%
2331
16th to endDay
12%6%245%35%5%5%8%38%
2431
June1st to 15thDay
10%5%25%5%35%5%6%8%40%
2490
16th to endDay
9%5%25%6%47%6%6%9%35%
2520
July1st to 15thDay
7%425%5%36%5%5%9%42%
2520
16th to endDay
7%425%6%36%6%7%9%40%
2537
August1st to 15thDay
6%5%25%6%47%5%7%9%40%
2340
16th to endDay
10%425%5%35%6%7%9%38%
2441
September1st to 15thDay
12%5%25%5%3446%7%41%
2019
16th to endDay
12%5%24435%45%8%43%
1980
October1st to 15thDay
15%6%27%5%2445%5%41%
1899
16th to endDay
20%7%36%5%3446%5%33%
1822
November1st to 15thDay
14%8%36%43445%6%39%
1717
16th to endDay
19%13%36%6%24346%29%
1755
December1st to 15thDay
16%14%6%9%7%23446%21%
1755
16th to endDay
21%15%7%10%6%2445%6%14%
1683
January1st to 15thNight
21%13%46%5%34445%24%
2716
16th to endNight
14%13%6%9%7%5%5%5%45%21%
2769
February1st to 15thNight
16%15%5%8%6%33435%25%
2395
16th to endNight
17%10%5%7%6%45%445%27%
1893
March1st to 15thNight
18%10%37%434445%32%
2067
16th to endNight
14%9%35%5%3445%6%35%
2112
April1st to 15thNight
18%8%35%444447%34%
1821
16th to endNight
15%7%35%5%2445%6%39%
1620
May1st to 15thNight
18%6%26%5%36%45%7%31%
1620
16th to endNight
11%6%35%5%345%5%8%42%
1682
June1st to 15thNight
9%425%5%25%5%6%7%45%
1467
16th to endNight
8%425%4246%8%10%42%
1440
July1st to 15thNight
6%3244245%5%8%52%
1440
16th to endNight
5%3135%2447%9%51%
1628
August1st to 15thNight
43145%25%47%10%48%
1620
16th to endNight
8%42442445%5%52%
1758
September1st to 15thNight
9%414433346%52%
1929
16th to endNight
11%425%432447%49%
1980
October1st to 15thNight
14%7%25%42435%6%43%
2059
16th to endNight
19%8%25%5%24445%36%
2400
November1st to 15thNight
15%7%25%42445%7%40%
2471
16th to endNight
21%9%37%5%3445%6%28%
2535
December1st to 15thNight
18%13%5%8%6%33346%24%
2535
16th to endNight
23%15%5%8%6%3445%5%17%
2889

Percentage Cloud Cover SE (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
20%14%5%8%7%445%45%19%
1552
16th to endDay
17%17%7%9%7%34445%17%
1805
February1st to 15thDay
15%14%5%10%7%46%445%22%
1728
16th to endDay
15%13%5%9%7%36%346%23%
1580
March1st to 15thDay
19%12%5%8%5%235%46%25%
1881
16th to endDay
20%10%47%5%33345%29%
2111
April1st to 15thDay
19%9%35%5%35%447%29%
2134
16th to endDay
17%8%25%424447%38%
2340
May1st to 15thDay
17%8%37%5%35%35%8%30%
2331
16th to endDay
13%5%345%35%5%6%7%39%
2431
June1st to 15thDay
11%425%5%35%5%6%7%41%
2490
16th to endDay
10%5%35%6%46%6%6%8%36%
2520
July1st to 15thDay
7%425%5%35%5%5%9%43%
2520
16th to endDay
8%425%5%36%6%6%10%41%
2537
August1st to 15thDay
7%425%7%36%5%7%8%41%
2340
16th to endDay
10%4246%35%6%7%9%38%
2441
September1st to 15thDay
13%5%25%5%345%5%7%41%
2019
16th to endDay
13%5%14425%5%5%8%43%
1980
October1st to 15thDay
15%5%36%5%3345%5%41%
1899
16th to endDay
19%8%26%5%3345%5%33%
1822
November1st to 15thDay
14%8%26%43445%6%38%
1717
16th to endDay
19%12%46%5%24446%29%
1755
December1st to 15thDay
17%14%6%9%6%33446%22%
1755
16th to endDay
21%15%7%10%6%3435%6%15%
1683
January1st to 15thNight
21%13%46%6%3445%5%24%
2716
16th to endNight
14%14%6%9%8%45%445%21%
2769
February1st to 15thNight
16%15%5%9%5%34345%26%
2388
16th to endNight
17%11%5%8%5%36%445%27%
1893
March1st to 15thNight
19%10%47%433345%32%
2079
16th to endNight
15%8%36%5%34447%35%
2112
April1st to 15thNight
18%7%35%434446%34%
1821
16th to endNight
15%7%26%43445%6%39%
1620
May1st to 15thNight
19%5%27%5%35%45%6%32%
1619
16th to endNight
11%5%25%5%245%47%43%
1682
June1st to 15thNight
10%425%5%25%5%5%7%45%
1467
16th to endNight
8%4245%245%7%10%42%
1440
July1st to 15thNight
7%3244245%5%7%53%
1440
16th to endNight
5%3135%2446%9%52%
1628
August1st to 15thNight
5%4135%35%5%6%10%48%
1620
16th to endNight
9%415%424346%52%
1758
September1st to 15thNight
9%424433347%52%
1929
16th to endNight
11%325%423447%49%
1980
October1st to 15thNight
14%6%25%424346%43%
2059
16th to endNight
20%7%245%34445%37%
2400
November1st to 15thNight
15%7%25%42345%6%40%
2471
16th to endNight
21%9%47%5%3335%6%28%
2535
December1st to 15thNight
19%13%5%8%5%33346%25%
2535
16th to endNight
23%15%6%8%5%34445%18%
2889

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
66%5%10%13%3
1553
16th to endDay
68%411%9%4
1805
February1st to 15thDay
64%5%9%15%5%
1730
16th to endDay
62%411%15%41
1580
March1st to 15thDay
59%5%12%15%5%
1881
16th to endDay
57%310%21%5%
2112
April1st to 15thDay
53%411%18%11%
2134
16th to endDay
45%411%21%12%3
2340
May1st to 15thDay
51%6%11%19%10%1
2331
16th to endDay
42%6%11%24%12%1
2435
June1st to 15thDay
39%5%13%25%14%2
2490
16th to endDay
43%6%14%18%15%2
2520
July1st to 15thDay
37%6%11%23%19%2
2371
16th to endDay
36%7%14%24%15%1
2380
August1st to 15thDay
36%8%14%24%15%1
2327
16th to endDay
38%7%12%22%15%2
2441
September1st to 15thDay
39%5%11%24%16%1
2019
16th to endDay
36%6%10%29%16%
1980
October1st to 15thDay
43%411%24%14%1
1899
16th to endDay
50%414%20%9%
1822
November1st to 15thDay
46%410%21%15%1
1717
16th to endDay
56%413%18%7%
1755
December1st to 15thDay
63%411%15%5%
1755
16th to endDay
69%6%11%9%2
1683
January1st to 15thNight
60%410%15%8%
2716
16th to endNight
64%5%13%12%4
2769
February1st to 15thNight
60%5%10%16%5%1
2397
16th to endNight
58%5%10%19%6%
1893
March1st to 15thNight
53%5%11%18%9%1
2079
16th to endNight
48%5%11%23%9%1
2112
April1st to 15thNight
49%5%10%19%14%
1821
16th to endNight
45%411%19%16%3
1620
May1st to 15thNight
50%6%10%18%11%1
1620
16th to endNight
38%6%10%26%15%2
1684
June1st to 15thNight
36%7%11%26%17%1
1467
16th to endNight
34%7%14%23%17%2
1440
July1st to 15thNight
29%6%12%27%20%3
1360
16th to endNight
25%8%15%25%21%3
1523
August1st to 15thNight
28%7%15%28%18%1
1609
16th to endNight
32%5%12%24%20%4
1758
September1st to 15thNight
33%412%27%20%2
1929
16th to endNight
33%5%11%27%20%1
1980
October1st to 15thNight
40%5%12%22%19%1
2059
16th to endNight
48%5%10%24%9%1
2400
November1st to 15thNight
42%412%23%14%1
2471
16th to endNight
55%312%20%7%
2535
December1st to 15thNight
60%412%14%8%
2535
16th to endNight
67%5%10%11%4
2889

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
22%17%35%17%5%1
135
16th to endDay
34%18%34%11%1
144
February1st to 15thDay
26%22%39%9%1
126
16th to endDay
20%18%45%13%1
81
March1st to 15thDay
29%17%28%19%5%
171
16th to endDay
25%12%35%15%9%1
288
April1st to 15thDay
20%14%32%23%7%1
270
16th to endDay
21%9%32%17%12%6%
270
May1st to 15thDay
23%9%30%18%12%5%
288
16th to endDay
15%10%28%21%15%9%
331
June1st to 15thDay
9%7%32%32%14%4
465
16th to endDay
13%8%29%30%12%5%
495
July1st to 15thDay
9%429%28%19%8%
475
16th to endDay
9%422%28%21%13%
397
August1st to 15thDay
10%216%30%22%17%
313
16th to endDay
14%314%23%25%18%
332
September1st to 15thDay
14%317%25%25%13%
315
16th to endDay
14%6%15%19%28%16%
314
October1st to 15thDay
17%6%23%26%17%8%
315
16th to endDay
18%14%31%27%5%1
238
November1st to 15thDay
21%9%26%24%13%4
135
16th to endDay
22%25%34%13%3
135
December1st to 15thDay
21%32%25%13%6%
135
16th to endDay
25%26%36%10%
144
January1st to 15thNight
28%14%32%18%5%
975
16th to endNight
20%15%38%20%4
897
February1st to 15thNight
24%13%35%23%2
753
16th to endNight
24%11%33%25%4
631
March1st to 15thNight
23%10%29%29%6%
720
16th to endNight
17%12%32%27%9%
768
April1st to 15thNight
21%12%33%25%5%
587
16th to endNight
19%8%32%28%9%1
540
May1st to 15thNight
20%5%27%31%12%1
540
16th to endNight
14%326%32%19%2
563
June1st to 15thNight
11%326%40%17%
540
16th to endNight
11%124%38%22%1
540
July1st to 15thNight
9%219%40%25%2
510
16th to endNight
5%217%40%29%4
564
August1st to 15thNight
7%214%41%28%5%
539
16th to endNight
10%111%35%35%5%
573
September1st to 15thNight
11%418%32%28%4
669
16th to endNight
12%317%30%31%4
717
October1st to 15thNight
17%8%21%28%20%3
720
16th to endNight
23%12%31%23%7%
768
November1st to 15thNight
18%11%30%27%10%2
760
16th to endNight
26%13%29%21%8%
780
December1st to 15thNight
26%13%34%20%4
780
16th to endNight
29%13%33%19%3
1017
Page generated at 2018-02-13 20:46:10. Version ac04

Copyright 2018 A. Danko


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