Columbus
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Columbus clear sky chart from 2005-11-05 to 2017-08-12.

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
53%
15259
23%
46544
18%
15213
59%
15213
31%
27853

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
37%
899
23%
2327
10%
895
44%
895
28%
1545
January16th to endNight
37%
954
24%
2490
10%
954
44%
954
29%
1638
February1st to 15thNight
39%
704
24%
2108
12%
699
48%
699
27%
1316
February16th to endNight
28%
578
25%
1840
10%
578
40%
578
25%
1128
March1st to 15thNight
34%
540
25%
1980
14%
540
48%
540
21%
1228
March16th to endNight
38%
576
22%
2112
17%
576
47%
576
26%
1218
April1st to 15thNight
35%
539
20%
1977
13%
539
46%
539
23%
1166
April16th to endNight
36%
540
22%
1825
18%
540
45%
540
25%
1123
May1st to 15thNight
41%
539
21%
1624
15%
539
50%
539
28%
1016
May16th to endNight
57%
562
23%
1684
22%
561
63%
561
31%
1026
June1st to 15thNight
76%
540
20%
1620
24%
540
78%
540
44%
850
June16th to endNight
78%
540
17%
1620
20%
540
80%
540
34%
960
July1st to 15thNight
80%
510
17%
1530
23%
510
80%
510
40%
854
July16th to endNight
85%
564
21%
1594
25%
531
87%
531
41%
875
August1st to 15thNight
90%
527
27%
1575
31%
524
90%
524
55%
751
August16th to endNight
80%
525
15%
1829
18%
525
80%
525
28%
1088
September1st to 15thNight
77%
495
18%
1815
22%
495
78%
495
31%
1036
September16th to endNight
70%
492
25%
1815
28%
492
71%
492
30%
1022
October1st to 15thNight
73%
555
33%
1875
32%
555
76%
555
42%
948
October16th to endNight
64%
704
34%
2112
26%
704
68%
704
45%
1096
November1st to 15thNight
55%
700
27%
2100
19%
700
59%
700
32%
1263
November16th to endNight
51%
816
30%
2256
19%
816
57%
816
35%
1339
December1st to 15thNight
38%
900
24%
2340
13%
900
43%
900
26%
1610
December16th to endNight
35%
960
20%
2496
9%
960
40%
960
23%
1757

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
11%5%25%5%35%5%6%7%40%
47417
Night
11%5%2442345%7%48%
46744
TransparencyDay
40%7%11%17%15%7%
47117
Night
34%6%13%20%16%9%
46549
SeeingDay
10%316%27%27%13%
5224
Night
13%421%34%22%2
15262

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
19%6%25%323345%42%
1611
16th to endDay
18%6%24313236%47%
1743
February1st to 15thDay
17%6%15%422336%46%
1750
16th to endDay
16%6%25%42435%5%43%
1633
March1st to 15thDay
21%8%25%42334438%
1980
16th to endDay
15%6%35%5%2435%6%42%
2110
April1st to 15thDay
13%6%345%35%447%40%
1971
16th to endDay
14%6%36%43335%6%40%
2133
May1st to 15thDay
9%6%46%5%45%5%6%8%36%
2324
16th to endDay
9%5%25%6%36%6%7%10%35%
2430
June1st to 15thDay
3325%6%47%7%7%9%42%
2340
16th to endDay
6%5%35%8%5%9%9%7%9%29%
2340
July1st to 15thDay
8%435%7%46%7%9%10%33%
2340
16th to endDay
5%326%8%48%7%9%12%31%
2466
August1st to 15thDay
22145%47%7%8%12%43%
2289
16th to endDay
6%5%26%7%5%7%7%7%10%33%
2016
September1st to 15thDay
8%436%7%46%6%7%8%35%
1815
16th to endDay
7%5%35%6%46%5%5%8%41%
1815
October1st to 15thDay
8%5%245%3446%7%48%
1744
16th to endDay
8%313323446%58%
1760
November1st to 15thDay
9%5%26%6%24447%45%
1758
16th to endDay
13%5%24313345%51%
1701
December1st to 15thDay
18%9%36%5%24235%36%
1620
16th to endDay
17%7%35%5%25%445%38%
1728
January1st to 15thNight
19%7%23322336%44%
2327
16th to endNight
19%5%24323235%46%
2490
February1st to 15thNight
17%7%23322345%46%
2102
16th to endNight
15%6%25%423345%47%
1840
March1st to 15thNight
18%6%24413336%43%
1980
16th to endNight
12%6%23323446%48%
2112
April1st to 15thNight
10%6%25%5%2345%7%45%
1977
16th to endNight
15%6%25%32435%7%43%
1825
May1st to 15thNight
8%5%25%5%25%5%6%9%42%
1623
16th to endNight
5%6%23435%5%6%11%44%
1683
June1st to 15thNight
421332446%9%58%
1620
16th to endNight
4223436%6%7%9%48%
1620
July1st to 15thNight
431431345%11%54%
1620
16th to endNight
2213335%5%6%14%51%
1702
August1st to 15thNight
11221346%11%64%
1585
16th to endNight
3325%5%35%6%8%13%43%
1829
September1st to 15thNight
6%325%425%46%10%48%
1815
16th to endNight
8%5%245%2345%8%49%
1815
October1st to 15thNight
6%213222348%60%
1875
16th to endNight
7%32331223464%
2112
November1st to 15thNight
9%6%25%42445%6%49%
2100
16th to endNight
11%424323336%54%
2256
December1st to 15thNight
19%7%25%424345%40%
2340
16th to endNight
18%9%35%5%2334439%
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
45%37%12%20%10%
1612
16th to endDay
40%27%14%19%14%
1743
February1st to 15thDay
42%36%16%17%14%
1751
16th to endDay
43%47%13%20%10%
1633
March1st to 15thDay
47%48%11%18%9%
1980
16th to endDay
43%47%15%20%8%
2112
April1st to 15thDay
43%5%7%16%16%10%
1971
16th to endDay
44%5%8%18%15%8%
2133
May1st to 15thDay
43%7%11%15%14%7%
2324
16th to endDay
41%8%13%17%15%3
2434
June1st to 15thDay
34%9%13%20%18%3
2340
16th to endDay
44%12%13%19%9%
2340
July1st to 15thDay
41%9%18%20%10%
2201
16th to endDay
37%12%22%22%3
2311
August1st to 15thDay
28%11%21%28%9%
2275
16th to endDay
44%12%18%16%7%1
2016
September1st to 15thDay
42%9%15%17%9%3
1815
16th to endDay
38%8%11%16%17%8%
1815
October1st to 15thDay
33%6%9%19%16%15%
1744
16th to endDay
28%35%17%26%18%
1760
November1st to 15thDay
38%6%11%15%18%10%
1758
16th to endDay
36%47%12%18%20%
1701
December1st to 15thDay
50%45%15%15%7%
1620
16th to endDay
47%47%14%16%8%
1728
January1st to 15thNight
41%36%14%19%14%
2327
16th to endNight
41%35%15%18%15%
2490
February1st to 15thNight
40%37%13%18%16%
2112
16th to endNight
40%37%14%19%13%
1840
March1st to 15thNight
43%47%14%18%10%
1980
16th to endNight
36%5%10%16%20%10%
2112
April1st to 15thNight
38%5%11%17%15%11%
1977
16th to endNight
40%5%12%16%14%10%
1825
May1st to 15thNight
36%7%12%20%13%9%
1624
16th to endNight
32%8%16%24%14%3
1685
June1st to 15thNight
22%7%17%29%22%2
1620
16th to endNight
28%9%21%27%10%1
1620
July1st to 15thNight
24%8%25%33%7%
1530
16th to endNight
20%11%30%31%5%
1594
August1st to 15thNight
13%7%28%38%11%
1575
16th to endNight
27%14%27%23%5%1
1829
September1st to 15thNight
30%8%23%23%11%3
1815
16th to endNight
32%6%14%19%18%7%
1815
October1st to 15thNight
23%5%12%25%19%13%
1875
16th to endNight
25%27%16%27%21%
2112
November1st to 15thNight
34%6%10%20%18%9%
2100
16th to endNight
32%48%13%20%20%
2256
December1st to 15thNight
44%5%8%18%14%8%
2340
16th to endNight
47%46%14%15%11%
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
23%5%33%27%10%
90
16th to endDay
19%13%35%15%14%1
96
February1st to 15thDay
10%18%32%26%10%2
90
16th to endDay
13%11%41%27%6%
81
March1st to 15thDay
30%12%30%13%13%1
90
16th to endDay
15%11%22%36%12%1
96
April1st to 15thDay
10%11%31%32%14%1
90
16th to endDay
19%429%25%19%
243
May1st to 15thDay
12%8%40%26%11%
461
16th to endDay
15%327%34%16%2
517
June1st to 15thDay
5%9%35%37%11%
495
16th to endDay
9%9%31%31%18%
495
July1st to 15thDay
6%15%28%36%21%
475
16th to endDay
4321%43%26%
515
August1st to 15thDay
4320%42%29%
474
16th to endDay
10%15%22%35%25%
184
September1st to 15thDay
5%411%36%42%
90
16th to endDay
3312%44%36%
90
October1st to 15thDay
1334%44%16%
90
16th to endDay
18%7%35%30%8%
96
November1st to 15thDay
15%5%21%31%18%7%
90
16th to endDay
17%12%22%28%11%7%
90
December1st to 15thDay
33%424%17%12%7%
90
16th to endDay
25%15%33%18%6%1
96
January1st to 15thNight
21%9%26%31%11%
900
16th to endNight
21%8%29%33%7%
954
February1st to 15thNight
21%10%25%34%7%
704
16th to endNight
19%9%38%27%3
578
March1st to 15thNight
22%7%33%32%5%
540
16th to endNight
14%7%35%33%8%
576
April1st to 15thNight
13%7%38%33%6%
539
16th to endNight
19%6%33%29%10%
540
May1st to 15thNight
11%5%38%35%9%
540
16th to endNight
7%226%44%17%
563
June1st to 15thNight
5%10%53%29%1
540
16th to endNight
5%8%43%36%5%
540
July1st to 15thNight
5%435%48%4
510
16th to endNight
2331%54%7%
564
August1st to 15thNight
1132%55%8%
527
16th to endNight
4128%59%6%
525
September1st to 15thNight
7%426%53%8%
495
16th to endNight
9%7%25%47%8%
492
October1st to 15thNight
7%112%38%35%3
555
16th to endNight
9%319%37%26%3
704
November1st to 15thNight
12%323%38%19%2
700
16th to endNight
15%5%24%35%18%1
816
December1st to 15thNight
23%7%25%29%13%
900
16th to endNight
24%8%25%30%10%
960
Page generated at 2017-08-13 13:16:33. Version ac04

Copyright 2017 A. Danko


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