Corydon Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Corydon Ridge Observatory clear sky chart from 2005-11-05 to 2017-09-16.

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
40%
15651
21%
46758
14%
15606
48%
15606
26%
29817

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
18%
900
16%
2506
6%
895
27%
895
17%
1812
January16th to endNight
19%
832
18%
2533
7%
832
30%
832
18%
1751
February1st to 15thNight
19%
704
16%
2112
5%
701
28%
701
17%
1489
February16th to endNight
16%
631
16%
1893
5%
631
25%
631
17%
1336
March1st to 15thNight
22%
720
17%
2136
8%
720
30%
720
18%
1474
March16th to endNight
28%
732
15%
2076
7%
732
36%
732
21%
1444
April1st to 15thNight
34%
539
23%
1797
13%
539
47%
539
26%
1064
April16th to endNight
38%
540
22%
1710
14%
540
48%
540
25%
1091
May1st to 15thNight
37%
540
17%
1619
10%
539
44%
539
23%
1095
May16th to endNight
56%
561
20%
1684
15%
561
60%
561
30%
1042
June1st to 15thNight
61%
540
21%
1491
16%
540
65%
540
41%
856
June16th to endNight
67%
540
22%
1440
16%
540
70%
540
43%
826
July1st to 15thNight
63%
510
18%
1360
14%
510
64%
510
35%
861
July16th to endNight
72%
564
24%
1525
21%
531
75%
531
42%
854
August1st to 15thNight
72%
539
26%
1637
24%
536
74%
536
41%
887
August16th to endNight
72%
573
26%
1910
26%
573
75%
573
40%
979
September1st to 15thNight
62%
621
27%
1881
23%
621
68%
621
37%
1082
September16th to endNight
55%
658
27%
1818
20%
658
59%
658
34%
1109
October1st to 15thNight
53%
660
34%
1815
23%
660
61%
660
38%
1040
October16th to endNight
36%
704
26%
2228
18%
704
47%
704
27%
1339
November1st to 15thNight
40%
700
29%
2276
20%
700
52%
700
29%
1306
November16th to endNight
33%
720
23%
2340
16%
720
43%
720
21%
1502
December1st to 15thNight
26%
720
15%
2340
9%
720
35%
720
16%
1637
December16th to endNight
20%
903
15%
2631
6%
903
29%
903
16%
1941

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%6%35%5%3445%7%39%
47983
Night
14%6%35%424447%42%
46944
TransparencyDay
43%310%23%15%2
47672
Night
42%310%23%16%3
46759
SeeingDay
16%8%24%24%16%9%
5694
Night
17%9%25%27%17%2
15653

By Month

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
21%8%39%432346%32%
1432
16th to endDay
14%10%47%5%24346%35%
1688
February1st to 15thDay
15%10%49%5%23347%34%
1750
16th to endDay
14%10%46%5%25%45%7%31%
1580
March1st to 15thDay
22%9%25%43323436%
1823
16th to endDay
16%8%36%5%35%45%7%32%
2156
April1st to 15thDay
15%7%25%42445%6%40%
2151
16th to endDay
17%6%25%6%34446%38%
2248
May1st to 15thDay
20%7%35%4245%5%6%33%
2331
16th to endDay
11%435%7%47%5%7%8%35%
2431
June1st to 15thDay
9%325%5%35%46%8%44%
2466
16th to endDay
7%4245%36%6%6%9%42%
2520
July1st to 15thDay
12%6%35%5%45%6%5%8%36%
2520
16th to endDay
7%415%5%36%6%7%10%39%
2534
August1st to 15thDay
7%5%15%5%45%6%6%9%42%
2310
16th to endDay
7%4245%35%6%6%9%43%
2292
September1st to 15thDay
14%5%25%42445%7%43%
2067
16th to endDay
12%5%26%5%2345%6%45%
1815
October1st to 15thDay
13%5%24422435%52%
1815
16th to endDay
16%5%23424246%46%
1642
November1st to 15thDay
13%5%24423346%48%
1582
16th to endDay
20%7%24314246%41%
1620
December1st to 15thDay
25%9%45%5%13235%31%
1620
16th to endDay
18%12%36%5%34336%31%
1590
January1st to 15thNight
17%9%5%7%7%23445%32%
2506
16th to endNight
17%10%36%5%2445%5%33%
2533
February1st to 15thNight
19%8%46%5%34445%33%
2103
16th to endNight
17%9%46%5%345%46%32%
1893
March1st to 15thNight
17%9%46%424445%36%
2136
16th to endNight
16%8%36%5%23447%35%
2076
April1st to 15thNight
13%6%24424448%44%
1797
16th to endNight
14%6%35%5%24447%41%
1710
May1st to 15thNight
16%5%36%5%35%5%5%6%37%
1619
16th to endNight
8%315%5%36%6%6%8%42%
1682
June1st to 15thNight
5%42442436%10%51%
1491
16th to endNight
6%214325%6%7%11%48%
1440
July1st to 15thNight
8%5%25%43445%8%47%
1440
16th to endNight
6%31443446%10%50%
1631
August1st to 15thNight
5%2233245%7%10%51%
1648
16th to endNight
43134235%6%11%51%
1910
September1st to 15thNight
13%31342345%9%49%
1881
16th to endNight
12%426%322346%49%
1818
October1st to 15thNight
8%5%14424346%55%
1815
16th to endNight
16%6%24422335%48%
2228
November1st to 15thNight
13%423423435%50%
2276
16th to endNight
18%9%25%423335%41%
2340
December1st to 15thNight
21%9%46%424335%32%
2340
16th to endNight
23%11%36%5%23435%30%
2631

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
54%39%19%11%1
1433
16th to endDay
50%210%27%8%1
1688
February1st to 15thDay
52%28%25%9%1
1752
16th to endDay
50%313%21%9%
1580
March1st to 15thDay
52%210%20%13%1
1823
16th to endDay
50%411%23%8%
2157
April1st to 15thDay
44%39%24%17%
2151
16th to endDay
45%310%23%13%3
2248
May1st to 15thDay
51%410%20%12%
2331
16th to endDay
43%5%14%19%14%2
2435
June1st to 15thDay
37%311%25%18%2
2466
16th to endDay
35%5%12%21%20%3
2520
July1st to 15thDay
44%411%20%14%4
2371
16th to endDay
34%6%16%25%14%2
2377
August1st to 15thDay
35%5%11%25%18%2
2297
16th to endDay
34%5%12%23%19%4
2292
September1st to 15thDay
40%310%21%18%5%
2067
16th to endDay
39%38%21%24%3
1815
October1st to 15thDay
35%25%28%24%3
1815
16th to endDay
40%19%27%17%2
1642
November1st to 15thDay
37%27%26%19%7%
1582
16th to endDay
45%27%24%18%1
1620
December1st to 15thDay
56%110%20%9%1
1620
16th to endDay
55%210%21%8%1
1590
January1st to 15thNight
54%28%19%13%1
2506
16th to endNight
51%210%24%9%1
2533
February1st to 15thNight
53%29%25%8%1
2112
16th to endNight
52%312%20%10%
1893
March1st to 15thNight
50%29%21%12%2
2136
16th to endNight
49%314%22%9%1
2076
April1st to 15thNight
39%210%24%20%3
1797
16th to endNight
44%28%25%14%5%
1710
May1st to 15thNight
46%410%24%12%1
1620
16th to endNight
37%5%13%21%17%4
1684
June1st to 15thNight
29%414%26%21%3
1491
16th to endNight
27%5%18%22%20%6%
1440
July1st to 15thNight
35%410%26%17%4
1360
16th to endNight
27%415%30%18%3
1525
August1st to 15thNight
26%415%28%20%4
1637
16th to endNight
25%415%29%20%4
1910
September1st to 15thNight
33%29%25%22%7%
1881
16th to endNight
36%26%22%25%5%
1818
October1st to 15thNight
30%37%26%26%5%
1815
16th to endNight
39%16%27%19%4
2228
November1st to 15thNight
35%27%23%23%7%
2276
16th to endNight
46%28%23%19%1
2340
December1st to 15thNight
54%210%20%10%1
2340
16th to endNight
56%210%18%9%1
2631

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
31%20%33%11%4
90
16th to endDay
17%35%33%12%1
96
February1st to 15thDay
20%36%32%10%1
90
16th to endDay
22%22%44%8%2
81
March1st to 15thDay
32%17%31%15%1
113
16th to endDay
20%17%37%16%6%2
288
April1st to 15thDay
20%12%29%25%9%1
270
16th to endDay
23%7%30%20%13%4
270
May1st to 15thDay
26%11%27%19%7%7%
288
16th to endDay
17%6%25%22%14%12%
331
June1st to 15thDay
9%6%20%33%20%9%
441
16th to endDay
9%6%28%28%17%9%
495
July1st to 15thDay
17%420%26%20%11%
475
16th to endDay
6%111%35%25%19%
394
August1st to 15thDay
11%314%22%24%23%
313
16th to endDay
10%114%28%27%16%
332
September1st to 15thDay
16%315%22%26%15%
315
16th to endDay
14%313%24%29%13%
254
October1st to 15thDay
15%5%24%25%18%10%
255
16th to endDay
19%10%35%23%10%
137
November1st to 15thDay
14%8%31%25%12%7%
90
16th to endDay
37%12%25%22%2
90
December1st to 15thDay
22%16%34%20%33
90
16th to endDay
32%18%40%7%1
96
January1st to 15thNight
24%16%36%19%3
900
16th to endNight
23%17%35%20%2
832
February1st to 15thNight
26%15%34%22%1
704
16th to endNight
22%17%38%19%2
631
March1st to 15thNight
24%15%33%22%4
720
16th to endNight
20%13%30%25%7%1
732
April1st to 15thNight
16%12%33%25%11%
539
16th to endNight
16%8%29%31%11%2
540
May1st to 15thNight
19%7%27%28%15%1
540
16th to endNight
10%320%34%23%7%
563
June1st to 15thNight
7%320%40%26%2
540
16th to endNight
5%217%40%30%3
540
July1st to 15thNight
11%111%36%34%3
510
16th to endNight
7%10%31%39%10%
564
August1st to 15thNight
7%19%34%39%7%
539
16th to endNight
6%19%34%42%5%
573
September1st to 15thNight
12%314%28%34%5%
621
16th to endNight
14%5%14%25%34%5%
658
October1st to 15thNight
11%7%20%28%25%6%
660
16th to endNight
20%9%29%26%12%
704
November1st to 15thNight
15%12%29%22%19%1
700
16th to endNight
23%14%25%26%9%
720
December1st to 15thNight
26%13%27%23%8%
720
16th to endNight
30%14%29%21%4
903
Page generated at 2017-09-16 17:07:03. Version ac04

Copyright 2017 A. Danko


Corydon Ridge Observatory Clear Sky Chart | Charts Home