Chiefland Astronomy Village
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chiefland Astronomy Village 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
55%
15630
22%
46557
16%
15591
61%
15591
31%
28133

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
38%
717
21%
2327
13%
716
48%
716
24%
1407
January16th to endNight
38%
768
24%
2409
16%
768
48%
768
25%
1515
February1st to 15thNight
40%
701
26%
2106
16%
699
51%
699
31%
1240
February16th to endNight
40%
631
25%
1893
14%
631
51%
631
29%
1159
March1st to 15thNight
43%
720
29%
1980
14%
720
55%
720
38%
1149
March16th to endNight
46%
768
28%
2112
17%
768
54%
768
39%
1195
April1st to 15thNight
46%
718
24%
1976
13%
718
53%
718
38%
1163
April16th to endNight
54%
636
29%
1800
19%
636
62%
636
44%
974
May1st to 15thNight
64%
539
28%
1619
19%
539
71%
539
46%
842
May16th to endNight
72%
561
26%
1682
20%
561
76%
561
42%
920
June1st to 15thNight
69%
540
16%
1620
14%
540
70%
540
30%
1020
June16th to endNight
77%
540
11%
1620
9%
540
78%
540
31%
1036
July1st to 15thNight
75%
510
10%
1530
9%
510
75%
510
24%
1034
July16th to endNight
78%
564
8%
1595
8%
531
80%
531
25%
1080
August1st to 15thNight
74%
527
7%
1626
7%
524
74%
524
25%
1069
August16th to endNight
65%
601
12%
1826
12%
601
66%
601
22%
1242
September1st to 15thNight
64%
660
10%
1815
10%
660
64%
660
22%
1285
September16th to endNight
58%
657
17%
1815
14%
657
61%
657
25%
1251
October1st to 15thNight
64%
660
28%
1838
25%
660
68%
660
38%
1084
October16th to endNight
58%
704
31%
2112
27%
704
66%
704
37%
1189
November1st to 15thNight
54%
700
31%
2101
24%
700
65%
700
40%
1136
November16th to endNight
45%
720
29%
2319
21%
720
57%
720
33%
1287
December1st to 15thNight
44%
720
27%
2340
22%
720
54%
720
29%
1375
December16th to endNight
46%
768
25%
2496
20%
768
55%
768
28%
1481

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
9%5%25%5%35%5%6%8%39%
47401
Night
8%425%4245%6%9%46%
46763
TransparencyDay
40%5%13%18%14%7%
47102
Night
34%5%14%20%16%7%
46566
SeeingDay
10%415%23%25%20%
5495
Night
10%5%20%31%25%7%
15639

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
12%7%25%5%24448%43%
1611
16th to endDay
12%5%235%23447%47%
1814
February1st to 15thDay
16%424324335%49%
1750
16th to endDay
11%5%25%42335%5%50%
1580
March1st to 15thDay
9%3243133410%52%
1980
16th to endDay
9%5%1432445%8%50%
2111
April1st to 15thDay
8%324445%5%5%8%48%
1972
16th to endDay
7%41332446%8%51%
2168
May1st to 15thDay
5%414435%5%5%8%50%
2331
16th to endDay
6%325%6%46%7%6%8%42%
2431
June1st to 15thDay
9%5%36%6%47%7%8%12%29%
2340
16th to endDay
8%5%25%6%48%8%8%11%29%
2340
July1st to 15thDay
9%426%8%48%9%9%12%23%
2340
16th to endDay
8%5%38%8%6%11%8%8%10%21%
2465
August1st to 15thDay
11%5%35%7%6%8%8%10%11%19%
2233
16th to endDay
12%5%37%9%6%6%8%8%9%21%
2012
September1st to 15thDay
10%6%39%9%5%7%7%7%9%23%
1815
16th to endDay
12%8%37%8%5%6%6%5%8%27%
1815
October1st to 15thDay
9%436%7%35%5%5%5%43%
1790
16th to endDay
8%3245%34446%52%
1760
November1st to 15thDay
7%42332435%8%54%
1757
16th to endDay
10%42442435%6%50%
1638
December1st to 15thDay
11%7%3442345%7%44%
1620
16th to endDay
10%5%24435%5%6%8%43%
1728
January1st to 15thNight
12%6%35%424448%42%
2327
16th to endNight
15%5%24424447%43%
2409
February1st to 15thNight
11%6%24423336%51%
2103
16th to endNight
12%5%24424445%48%
1893
March1st to 15thNight
7%41432445%7%53%
1980
16th to endNight
8%424423346%55%
2112
April1st to 15thNight
7%42441445%7%51%
1976
16th to endNight
6%313423249%57%
1800
May1st to 15thNight
5%21332435%9%59%
1619
16th to endNight
5%31442346%8%55%
1682
June1st to 15thNight
10%4245%345%7%12%38%
1620
16th to endNight
6%315%437%6%8%13%38%
1620
July1st to 15thNight
4415%5%37%8%9%14%34%
1620
16th to endNight
2426%6%37%9%12%12%32%
1703
August1st to 15thNight
7%325%6%36%8%10%12%32%
1637
16th to endNight
7%5%36%6%45%6%7%11%35%
1826
September1st to 15thNight
8%5%27%6%36%6%8%13%30%
1815
16th to endNight
12%7%26%5%46%6%6%10%31%
1815
October1st to 15thNight
6%425%42445%8%50%
1838
16th to endNight
8%42442345%7%52%
2112
November1st to 15thNight
7%214333447%56%
2101
16th to endNight
9%324424447%51%
2319
December1st to 15thNight
13%6%24423448%46%
2340
16th to endNight
10%6%25%4345%47%45%
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
40%38%19%18%9%
1612
16th to endDay
36%28%19%22%10%
1814
February1st to 15thDay
39%16%14%21%16%
1752
16th to endDay
36%210%13%24%12%
1580
March1st to 15thDay
30%210%21%24%9%
1980
16th to endDay
33%39%22%19%11%
2112
April1st to 15thDay
32%49%20%23%9%
1972
16th to endDay
29%311%23%21%10%
2168
May1st to 15thDay
30%312%24%20%8%
2331
16th to endDay
36%5%14%23%16%4
2435
June1st to 15thDay
45%7%18%22%5%
2340
16th to endDay
45%8%20%19%6%
2340
July1st to 15thDay
47%11%26%13%1
2201
16th to endDay
52%8%23%11%2
2310
August1st to 15thDay
52%10%24%11%1
2220
16th to endDay
55%8%19%13%2
2012
September1st to 15thDay
52%8%20%11%5%
1815
16th to endDay
52%5%11%17%8%3
1815
October1st to 15thDay
41%48%15%17%13%
1790
16th to endDay
32%37%15%24%15%
1760
November1st to 15thDay
28%29%24%22%12%
1757
16th to endDay
34%27%18%22%13%
1638
December1st to 15thDay
38%29%23%18%6%
1620
16th to endDay
36%411%25%13%8%
1728
January1st to 15thNight
40%29%20%18%8%
2327
16th to endNight
41%36%14%23%10%
2409
February1st to 15thNight
36%17%16%21%15%
2112
16th to endNight
37%48%15%23%10%
1893
March1st to 15thNight
30%311%23%21%9%
1980
16th to endNight
30%211%24%19%11%
2112
April1st to 15thNight
31%411%21%23%8%
1976
16th to endNight
25%311%29%21%7%
1800
May1st to 15thNight
22%413%28%20%9%
1620
16th to endNight
26%5%18%27%20%2
1684
June1st to 15thNight
36%6%22%27%5%
1620
16th to endNight
33%10%27%22%5%
1620
July1st to 15thNight
38%12%29%16%2
1530
16th to endNight
35%15%33%12%3
1595
August1st to 15thNight
38%10%34%14%1
1626
16th to endNight
41%11%25%17%4
1826
September1st to 15thNight
43%10%25%13%5%
1815
16th to endNight
45%5%16%19%8%2
1815
October1st to 15thNight
31%412%18%20%12%
1838
16th to endNight
31%37%17%26%14%
2112
November1st to 15thNight
28%28%23%25%11%
2101
16th to endNight
32%38%20%19%16%
2319
December1st to 15thNight
37%38%28%14%7%
2340
16th to endNight
37%39%24%15%8%
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
15%16%38%13%11%4
90
16th to endDay
14%16%41%19%6%1
96
February1st to 15thDay
11%25%27%18%14%2
90
16th to endDay
11%18%37%27%6%
81
March1st to 15thDay
12%11%31%28%14%2
270
16th to endDay
10%7%26%30%22%2
288
April1st to 15thDay
9%12%25%27%22%3
270
16th to endDay
6%321%30%27%10%
270
May1st to 15thDay
8%5%16%30%22%16%
288
16th to endDay
7%17%24%33%25%
331
June1st to 15thDay
13%17%17%29%30%
315
16th to endDay
7%217%32%39%
315
July1st to 15thDay
5%1113%26%51%
305
16th to endDay
9%15%11%29%42%
326
August1st to 15thDay
15%5%12%25%39%
297
16th to endDay
10%1315%30%39%
268
September1st to 15thDay
13%418%33%29%
255
16th to endDay
14%28%19%36%19%
254
October1st to 15thDay
9%312%37%26%10%
255
16th to endDay
7%226%30%27%5%
272
November1st to 15thDay
9%420%35%24%6%
265
16th to endDay
12%137%26%17%4
108
December1st to 15thDay
5%11%44%28%8%1
90
16th to endDay
12%7%26%36%15%2
96
January1st to 15thNight
16%10%26%31%13%
720
16th to endNight
18%9%27%31%12%
768
February1st to 15thNight
14%10%31%31%11%
704
16th to endNight
13%10%29%39%6%
631
March1st to 15thNight
10%11%31%35%11%
720
16th to endNight
10%7%29%35%16%
768
April1st to 15thNight
8%5%33%34%16%
718
16th to endNight
7%5%27%38%20%1
636
May1st to 15thNight
6%221%41%23%3
540
16th to endNight
6%111%36%36%7%
563
June1st to 15thNight
11%7%27%38%13%
540
16th to endNight
7%1320%42%25%
540
July1st to 15thNight
5%1414%40%32%
510
16th to endNight
3212%54%27%
564
August1st to 15thNight
8%212%49%26%
527
16th to endNight
9%16%19%40%22%
601
September1st to 15thNight
10%26%23%37%20%
660
16th to endNight
16%11%30%35%6%
657
October1st to 15thNight
9%214%40%29%3
660
16th to endNight
10%320%36%27%1
704
November1st to 15thNight
8%5%25%38%19%2
700
16th to endNight
10%6%31%35%15%
720
December1st to 15thNight
15%8%25%33%17%
720
16th to endNight
13%9%25%34%16%1
768
Page generated at 2017-08-13 14:16:20. Version ac04

Copyright 2017 A. Danko


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