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 2018-03-21.

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%
16205
23%
49208
16%
16162
57%
16162
29%
30252

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%
780
23%
2522
9%
776
43%
776
22%
1558
January16th to endNight
27%
832
26%
2636
12%
832
42%
832
22%
1655
February1st to 15thNight
31%
764
24%
2291
10%
761
45%
761
26%
1430
February16th to endNight
24%
683
23%
2049
9%
683
37%
683
24%
1301
March1st to 15thNight
30%
780
23%
2248
11%
780
41%
780
28%
1405
March16th to endNight
39%
792
22%
2178
12%
792
45%
792
30%
1366
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
64%
693
20%
1953
18%
693
65%
693
28%
1294
September16th to endNight
65%
717
26%
1980
21%
717
68%
717
32%
1245
October1st to 15thNight
57%
720
32%
1980
25%
720
63%
720
39%
1154
October16th to endNight
52%
768
35%
2298
27%
768
64%
768
39%
1267
November1st to 15thNight
52%
760
29%
2471
25%
760
61%
760
36%
1330
November16th to endNight
41%
780
29%
2535
20%
780
54%
780
30%
1446
December1st to 15thNight
34%
780
23%
2535
14%
780
46%
780
25%
1558
December16th to endNight
31%
832
20%
2704
13%
832
40%
832
19%
1830

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%41%
49632
Night
11%5%2442445%7%45%
49408
TransparencyDay
39%6%11%19%17%4
49333
Night
36%5%10%20%20%6%
49211
SeeingDay
16%7%18%21%22%14%
5962
Night
14%7%23%28%22%4
16207

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
16%7%35%324445%42%
1746
16th to endDay
18%6%24314336%44%
1937
February1st to 15thDay
16%6%2442445%7%40%
1900
16th to endDay
19%6%3442345%5%40%
1710
March1st to 15thDay
16%6%25%5%23346%42%
2041
16th to endDay
16%5%245%35%45%7%39%
2173
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
12%5%25%5%25%6%6%8%38%
1993
16th to endDay
15%4243245%5%6%44%
1980
October1st to 15thDay
13%413323346%53%
1980
16th to endDay
11%5%1432233458%
1922
November1st to 15thDay
13%5%2331425%5%52%
1717
16th to endDay
13%5%25%424345%49%
1755
December1st to 15thDay
18%6%34423446%40%
1755
16th to endDay
24%8%35%423235%35%
1872
January1st to 15thNight
17%6%24324345%44%
2522
16th to endNight
17%6%245%23345%44%
2636
February1st to 15thNight
16%5%23324337%45%
2283
16th to endNight
16%5%25%423446%44%
2049
March1st to 15thNight
13%6%24423446%47%
2248
16th to endNight
11%5%25%42435%7%47%
2178
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
9%5%25%6%36%5%5%9%41%
1953
16th to endNight
12%5%1342445%6%48%
1980
October1st to 15thNight
10%323323346%55%
1980
16th to endNight
9%41441323459%
2298
November1st to 15thNight
12%313313346%56%
2471
16th to endNight
12%5%24323346%51%
2535
December1st to 15thNight
14%7%34422446%44%
2535
16th to endNight
21%7%25%424347%35%
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
43%310%15%23%4
1747
16th to endDay
41%35%19%21%7%
1937
February1st to 15thDay
42%48%19%21%3
1902
16th to endDay
44%48%19%18%5%
1710
March1st to 15thDay
42%49%17%20%6%
2041
16th to endDay
42%5%12%20%16%3
2174
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
1993
16th to endDay
37%6%10%20%20%3
1980
October1st to 15thDay
33%49%19%26%7%
1980
16th to endDay
30%35%16%32%11%
1922
November1st to 15thDay
34%26%16%30%9%
1717
16th to endDay
37%36%16%27%8%
1755
December1st to 15thDay
44%47%20%16%6%
1755
16th to endDay
53%27%17%13%4
1872
January1st to 15thNight
41%38%18%23%5%
2522
16th to endNight
42%35%18%22%7%
2636
February1st to 15thNight
40%28%19%20%8%
2292
16th to endNight
41%36%20%22%5%
2049
March1st to 15thNight
37%49%19%20%8%
2248
16th to endNight
36%410%24%19%4
2178
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%19%15%4
1953
16th to endNight
35%7%10%22%18%5%
1980
October1st to 15thNight
29%410%19%27%8%
1980
16th to endNight
29%2415%33%13%
2298
November1st to 15thNight
29%37%17%30%11%
2471
16th to endNight
34%35%18%27%10%
2535
December1st to 15thNight
39%49%20%18%7%
2535
16th to endNight
49%38%16%17%4
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%20%34%17%5%1
135
16th to endDay
20%26%34%11%6%1
144
February1st to 15thDay
23%20%40%13%2
135
16th to endDay
27%14%38%20%
120
March1st to 15thDay
21%19%29%22%7%
226
16th to endDay
17%13%30%24%12%2
311
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
15%48%20%28%23%
315
16th to endDay
17%112%23%31%14%
314
October1st to 15thDay
20%118%26%25%8%
315
16th to endDay
13%7%20%24%26%7%
333
November1st to 15thDay
25%10%22%22%17%1
135
16th to endDay
7%13%31%28%15%3
135
December1st to 15thDay
24%17%29%22%6%
135
16th to endDay
34%15%33%12%4
144
January1st to 15thNight
21%15%31%23%7%
780
16th to endNight
20%14%34%26%5%
832
February1st to 15thNight
20%12%32%29%4
764
16th to endNight
19%14%37%24%3
683
March1st to 15thNight
17%12%37%26%6%
780
16th to endNight
15%10%29%30%13%
792
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%40%11%
693
16th to endNight
16%11%33%34%3
717
October1st to 15thNight
12%420%29%26%6%
720
16th to endNight
11%6%24%30%22%3
768
November1st to 15thNight
13%5%23%30%23%2
760
16th to endNight
16%11%28%27%15%
780
December1st to 15thNight
17%11%31%28%10%
780
16th to endNight
26%10%29%26%7%
832
Page generated at 2018-03-22 11:34:26. Version ac04

Copyright 2018 A. Danko


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