Marietta
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marietta clear sky chart from 2005-11-05 to

2017-09-12
.

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
49%
15444
23%
46884
16%
15401
57%
15401
29%
28876

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
27%
720
23%
2327
9%
716
43%
716
22%
1439
January16th to endNight
25%
768
24%
2433
11%
768
41%
768
22%
1548
February1st to 15thNight
31%
704
25%
2111
10%
701
46%
701
28%
1287
February16th to endNight
24%
631
24%
1893
9%
631
37%
631
25%
1187
March1st to 15thNight
31%
720
23%
2075
11%
720
41%
720
28%
1308
March16th to endNight
40%
768
21%
2112
13%
768
46%
768
30%
1323
April1st to 15thNight
42%
617
25%
1875
16%
617
53%
617
33%
1086
April16th to endNight
52%
540
26%
1716
18%
540
61%
540
34%
983
May1st to 15thNight
52%
540
21%
1620
13%
540
59%
540
31%
994
May16th to endNight
65%
561
21%
1682
15%
561
69%
561
34%
1013
June1st to 15thNight
74%
540
17%
1620
15%
540
75%
540
31%
1017
June16th to endNight
79%
540
17%
1620
14%
540
80%
540
35%
975
July1st to 15thNight
72%
510
14%
1530
12%
510
72%
510
28%
989
July16th to endNight
72%
564
17%
1595
15%
531
74%
531
29%
1023
August1st to 15thNight
74%
539
18%
1660
19%
536
75%
536
27%
1061
August16th to endNight
67%
573
19%
1910
21%
573
68%
573
21%
1272
September1st to 15thNight
65%
680
19%
1917
18%
680
66%
680
28%
1271
September16th to endNight
61%
657
23%
1815
18%
657
65%
657
29%
1178
October1st to 15thNight
56%
660
33%
1815
26%
660
62%
660
38%
1067
October16th to endNight
52%
704
34%
2106
26%
704
64%
704
38%
1171
November1st to 15thNight
50%
700
31%
2276
26%
700
61%
700
36%
1209
November16th to endNight
39%
720
27%
2340
18%
720
53%
720
29%
1357
December1st to 15thNight
35%
720
23%
2340
14%
720
46%
720
25%
1434
December16th to endNight
31%
768
20%
2496
13%
768
41%
768
19%
1684

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
13%5%25%5%35%5%6%8%40%
47766
Night
11%5%2442445%7%45%
47084
TransparencyDay
39%6%11%19%17%4
47467
Night
36%5%10%20%20%6%
46887
SeeingDay
15%6%18%21%22%15%
5327
Night
14%7%22%28%22%4
15446

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
17%7%35%324445%42%
1611
16th to endDay
18%7%24314436%43%
1788
February1st to 15thDay
15%6%2432445%7%42%
1750
16th to endDay
18%5%3442345%5%41%
1580
March1st to 15thDay
16%6%25%5%2335%7%41%
1884
16th to endDay
16%5%24435%45%7%40%
2111
April1st to 15thDay
12%5%25%43445%6%45%
2082
16th to endDay
11%32443446%7%47%
2244
May1st to 15thDay
10%426%5%25%5%5%7%43%
2331
16th to endDay
9%425%5%35%5%5%9%41%
2431
June1st to 15thDay
8%5%25%5%35%7%8%11%34%
2340
16th to endDay
5%2135%36%7%7%12%43%
2340
July1st to 15thDay
10%425%6%5%7%8%8%10%30%
2340
16th to endDay
7%425%6%48%9%8%11%31%
2465
August1st to 15thDay
8%5%25%6%5%7%8%8%11%31%
2286
16th to endDay
12%6%36%7%46%6%7%10%26%
2292
September1st to 15thDay
11%5%26%5%25%6%6%8%38%
1949
16th to endDay
16%5%244245%5%6%41%
1815
October1st to 15thDay
13%413323346%53%
1815
16th to endDay
12%5%1432233457%
1762
November1st to 15thDay
12%5%23314245%53%
1582
16th to endDay
14%5%25%32335%5%48%
1620
December1st to 15thDay
18%6%345%23447%39%
1620
16th to endDay
24%8%35%433235%35%
1728
January1st to 15thNight
18%6%24224345%44%
2327
16th to endNight
17%6%345%23345%42%
2433
February1st to 15thNight
15%5%23324337%47%
2103
16th to endNight
16%5%25%423345%45%
1893
March1st to 15thNight
13%6%24423446%46%
2075
16th to endNight
11%5%25%42435%7%47%
2112
April1st to 15thNight
12%5%2332435%7%49%
1875
16th to endNight
10%4243335%5%8%49%
1716
May1st to 15thNight
7%5%35%5%35%5%6%8%45%
1619
16th to endNight
6%415%435%5%6%9%46%
1682
June1st to 15thNight
5%334435%6%8%14%40%
1620
16th to endNight
4215%5%35%7%8%11%44%
1620
July1st to 15thNight
5%425%6%37%6%8%11%36%
1620
16th to endNight
4426%5%46%6%9%12%37%
1703
August1st to 15thNight
5%426%5%45%5%9%10%39%
1671
16th to endNight
11%5%345%45%6%7%10%35%
1910
September1st to 15thNight
8%5%25%6%36%5%5%9%41%
1917
16th to endNight
14%6%1343445%6%46%
1815
October1st to 15thNight
10%323423346%54%
1815
16th to endNight
9%41441323459%
2106
November1st to 15thNight
12%313313245%57%
2276
16th to endNight
13%5%24323346%50%
2340
December1st to 15thNight
13%7%35%422446%44%
2340
16th to endNight
21%7%25%424347%35%
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
43%39%14%23%4
1612
16th to endDay
42%35%19%21%6%
1788
February1st to 15thDay
40%48%20%22%3
1752
16th to endDay
43%37%19%19%6%
1580
March1st to 15thDay
43%49%17%19%4
1884
16th to endDay
41%5%12%20%16%3
2112
April1st to 15thDay
38%5%10%21%19%5%
2082
16th to endDay
34%5%9%24%22%4
2244
May1st to 15thDay
38%5%12%20%19%3
2331
16th to endDay
36%7%14%25%14%2
2435
June1st to 15thDay
38%9%18%23%8%1
2340
16th to endDay
30%8%17%27%14%2
2340
July1st to 15thDay
41%12%19%17%8%1
2201
16th to endDay
40%13%17%18%8%1
2310
August1st to 15thDay
40%12%17%19%9%1
2273
16th to endDay
48%10%14%15%10%
2292
September1st to 15thDay
40%8%14%18%15%3
1949
16th to endDay
40%6%10%18%20%4
1815
October1st to 15thDay
32%49%18%26%8%
1815
16th to endDay
30%35%16%31%10%
1762
November1st to 15thDay
32%26%16%31%10%
1582
16th to endDay
38%36%16%27%7%
1620
December1st to 15thDay
44%47%20%15%7%
1620
16th to endDay
53%27%16%14%5%
1728
January1st to 15thNight
41%38%18%23%5%
2327
16th to endNight
43%35%18%22%7%
2433
February1st to 15thNight
38%28%20%21%9%
2112
16th to endNight
41%35%20%23%5%
1893
March1st to 15thNight
38%410%19%19%8%
2075
16th to endNight
36%49%24%19%4
2112
April1st to 15thNight
33%38%24%23%6%
1875
16th to endNight
31%5%10%23%21%8%
1716
May1st to 15thNight
35%6%14%20%20%2
1620
16th to endNight
31%7%14%26%15%3
1684
June1st to 15thNight
31%11%20%24%11%1
1620
16th to endNight
29%10%19%21%16%2
1620
July1st to 15thNight
35%10%18%23%8%2
1530
16th to endNight
34%10%20%19%11%2
1595
August1st to 15thNight
35%11%16%23%12%1
1660
16th to endNight
41%10%15%17%13%1
1910
September1st to 15thNight
37%9%13%18%15%4
1917
16th to endNight
38%7%10%21%17%6%
1815
October1st to 15thNight
30%410%17%27%8%
1815
16th to endNight
30%2416%32%13%
2106
November1st to 15thNight
29%26%16%32%12%
2276
16th to endNight
35%35%17%27%9%
2340
December1st to 15thNight
39%49%20%18%7%
2340
16th to endNight
48%38%15%18%4
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
17%16%35%21%6%2
90
16th to endDay
18%29%40%7%4
96
February1st to 15thDay
18%23%41%14%2
90
16th to endDay
24%14%41%18%
81
March1st to 15thDay
21%16%30%23%8%
174
16th to endDay
17%12%28%25%13%2
288
April1st to 15thDay
16%13%28%18%21%2
270
16th to endDay
14%321%29%25%5%
270
May1st to 15thDay
13%6%29%19%16%14%
288
16th to endDay
13%312%27%26%15%
331
June1st to 15thDay
11%19%17%31%29%
315
16th to endDay
8%9%25%24%32%
315
July1st to 15thDay
11%6%18%25%38%
305
16th to endDay
10%6%14%36%31%
326
August1st to 15thDay
15%7%20%32%24%
313
16th to endDay
16%17%23%27%23%
332
September1st to 15thDay
14%47%19%29%24%
299
16th to endDay
21%113%25%27%10%
254
October1st to 15thDay
19%120%23%25%8%
255
16th to endDay
14%5%20%23%27%7%
269
November1st to 15thDay
27%14%23%17%14%2
90
16th to endDay
8%12%32%27%14%4
90
December1st to 15thDay
22%16%36%16%7%
90
16th to endDay
35%11%33%14%5%
96
January1st to 15thNight
22%14%31%23%7%
720
16th to endNight
20%13%35%26%4
768
February1st to 15thNight
19%11%33%30%4
704
16th to endNight
18%15%37%24%3
631
March1st to 15thNight
16%12%36%26%6%
720
16th to endNight
15%10%28%31%13%
768
April1st to 15thNight
15%8%31%26%16%1
617
16th to endNight
13%5%25%35%17%2
540
May1st to 15thNight
10%5%25%31%24%2
540
16th to endNight
9%115%32%33%6%
563
June1st to 15thNight
7%9%31%39%11%
540
16th to endNight
318%30%44%12%
540
July1st to 15thNight
5%17%24%47%14%
510
16th to endNight
6%7%22%48%14%
564
August1st to 15thNight
7%5%25%49%10%
539
16th to endNight
13%17%25%43%9%
573
September1st to 15thNight
12%10%23%41%11%
680
16th to endNight
17%12%34%31%2
657
October1st to 15thNight
12%421%29%25%6%
660
16th to endNight
11%6%24%31%22%4
704
November1st to 15thNight
13%6%24%29%24%2
700
16th to endNight
17%11%28%27%14%
720
December1st to 15thNight
16%12%31%28%10%
720
16th to endNight
25%10%28%27%7%
768
Page generated at 2017-09-13 07:39:18. Version ac04

Copyright 2017 A. Danko


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