Trigg County Schools
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Trigg County Schools 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
46%
15636
23%
46768
16%
15591
53%
15591
29%
28849

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
26%
899
20%
2506
10%
895
35%
895
21%
1729
January16th to endNight
26%
913
21%
2498
9%
913
35%
913
24%
1689
February1st to 15thNight
23%
704
17%
2112
7%
701
31%
701
18%
1458
February16th to endNight
24%
631
20%
1893
8%
631
34%
631
21%
1257
March1st to 15thNight
28%
720
19%
2160
9%
720
36%
720
23%
1439
March16th to endNight
37%
637
18%
2014
12%
637
43%
637
23%
1307
April1st to 15thNight
40%
539
25%
1797
16%
539
53%
539
31%
1012
April16th to endNight
46%
540
24%
1800
18%
540
55%
540
29%
1047
May1st to 15thNight
44%
540
20%
1625
11%
539
52%
539
28%
1031
May16th to endNight
66%
562
20%
1668
17%
561
68%
561
33%
1011
June1st to 15thNight
67%
540
22%
1440
16%
540
70%
540
42%
836
June16th to endNight
76%
540
25%
1440
20%
540
78%
540
45%
819
July1st to 15thNight
71%
510
18%
1360
16%
510
72%
510
39%
823
July16th to endNight
77%
564
25%
1468
21%
531
78%
531
44%
836
August1st to 15thNight
76%
539
23%
1781
25%
536
77%
536
39%
936
August16th to endNight
73%
573
25%
1910
29%
573
75%
573
37%
1021
September1st to 15thNight
65%
555
25%
1792
26%
555
67%
555
33%
1020
September16th to endNight
59%
657
28%
1815
22%
657
62%
657
36%
1099
October1st to 15thNight
56%
660
34%
1842
25%
660
61%
660
38%
1077
October16th to endNight
48%
704
29%
2194
23%
704
55%
704
31%
1298
November1st to 15thNight
48%
700
32%
2276
26%
700
59%
700
35%
1243
November16th to endNight
37%
720
25%
2340
18%
720
47%
720
26%
1403
December1st to 15thNight
31%
729
19%
2349
13%
729
39%
729
19%
1578
December16th to endNight
28%
960
19%
2688
9%
960
37%
960
21%
1880

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
12%6%25%5%3445%7%41%
47894
Night
13%6%2442445%7%45%
46949
TransparencyDay
40%311%24%16%3
47577
Night
39%310%24%18%3
46770
SeeingDay
13%418%25%24%14%
5681
Night
17%7%22%30%19%3
15638

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
20%7%46%323436%36%
1432
16th to endDay
13%6%47%6%24446%39%
1722
February1st to 15thDay
15%10%36%5%23345%38%
1750
16th to endDay
16%10%36%5%24446%35%
1580
March1st to 15thDay
21%9%35%5%23445%36%
1800
16th to endDay
16%8%46%5%2445%5%35%
2217
April1st to 15thDay
13%5%25%5%2445%7%42%
2151
16th to endDay
14%6%36%43445%6%39%
2160
May1st to 15thDay
16%6%25%5%35%5%5%6%36%
2322
16th to endDay
9%5%36%6%35%5%6%9%38%
2443
June1st to 15thDay
7%3245%25%5%7%8%46%
2520
16th to endDay
43245%36%5%7%10%45%
2520
July1st to 15thDay
9%5%26%6%35%5%7%9%38%
2520
16th to endDay
5%3146%36%6%7%11%42%
2598
August1st to 15thDay
5%5%25%5%35%6%8%9%41%
2166
16th to endDay
8%425%5%35%5%6%10%42%
2292
September1st to 15thDay
10%5%25%4345%5%8%42%
2075
16th to endDay
11%5%34424446%48%
1815
October1st to 15thDay
12%414423346%51%
1787
16th to endDay
15%5%13323236%51%
1678
November1st to 15thDay
13%6%2331334453%
1582
16th to endDay
16%6%2432235%5%46%
1620
December1st to 15thDay
19%9%4433345%6%35%
1608
16th to endDay
18%11%24424346%35%
1536
January1st to 15thNight
18%9%35%5%23345%38%
2506
16th to endNight
15%8%36%5%33346%38%
2498
February1st to 15thNight
19%9%36%424425%36%
2103
16th to endNight
15%8%36%5%24346%37%
1893
March1st to 15thNight
16%8%35%423346%40%
2160
16th to endNight
15%7%36%5%2346%7%38%
2014
April1st to 15thNight
11%5%2332435%7%49%
1797
16th to endNight
14%42443445%7%46%
1800
May1st to 15thNight
15%5%245%2346%7%41%
1625
16th to endNight
6%325%6%36%5%6%9%45%
1667
June1st to 15thNight
7%42442346%8%51%
1440
16th to endNight
32135%25%5%7%12%49%
1440
July1st to 15thNight
7%4245%25%5%6%9%46%
1440
16th to endNight
5%323435%46%8%52%
1568
August1st to 15thNight
5%31433446%10%51%
1792
16th to endNight
6%3143245%5%10%50%
1910
September1st to 15thNight
11%5%2242345%8%48%
1792
16th to endNight
11%5%345%13446%50%
1815
October1st to 15thNight
11%414422335%54%
1842
16th to endNight
16%5%2341323451%
2194
November1st to 15thNight
12%5%23323346%53%
2276
16th to endNight
17%6%24323345%47%
2340
December1st to 15thNight
19%11%34423445%35%
2349
16th to endNight
22%9%35%33334437%
2688

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
50%27%25%12%1
1433
16th to endDay
45%39%29%9%1
1722
February1st to 15thDay
48%27%27%11%2
1752
16th to endDay
50%210%21%13%2
1580
March1st to 15thDay
51%28%20%13%3
1800
16th to endDay
49%312%25%9%
2218
April1st to 15thDay
39%29%23%20%3
2151
16th to endDay
44%38%27%13%2
2160
May1st to 15thDay
47%311%22%13%1
2322
16th to endDay
41%6%14%21%13%2
2447
June1st to 15thDay
32%413%28%18%2
2520
16th to endDay
30%6%13%24%20%4
2520
July1st to 15thDay
39%413%24%12%4
2371
16th to endDay
32%5%19%28%13%1
2435
August1st to 15thDay
35%6%13%26%17%2
2153
16th to endDay
35%412%25%18%3
2292
September1st to 15thDay
38%5%9%25%16%4
2075
16th to endDay
37%37%21%24%5%
1815
October1st to 15thDay
34%27%25%24%5%
1787
16th to endDay
35%2426%24%5%
1678
November1st to 15thDay
34%27%22%25%7%
1582
16th to endDay
40%17%29%16%3
1620
December1st to 15thDay
49%212%20%12%2
1608
16th to endDay
50%112%22%11%1
1536
January1st to 15thNight
49%28%21%16%1
2506
16th to endNight
46%210%23%14%1
2498
February1st to 15thNight
51%28%22%12%1
2112
16th to endNight
47%39%24%13%2
1893
March1st to 15thNight
46%29%19%16%5%
2160
16th to endNight
46%213%23%12%1
2014
April1st to 15thNight
33%310%26%20%4
1797
16th to endNight
36%36%28%21%2
1800
May1st to 15thNight
41%312%23%17%1
1626
16th to endNight
33%6%15%23%16%3
1669
June1st to 15thNight
28%415%27%21%2
1440
16th to endNight
25%5%15%27%20%5%
1440
July1st to 15thNight
31%415%27%15%5%
1360
16th to endNight
26%5%17%32%16%2
1468
August1st to 15thNight
26%5%15%27%22%2
1781
16th to endNight
28%5%14%28%19%4
1910
September1st to 15thNight
33%39%26%20%5%
1792
16th to endNight
34%37%21%25%8%
1815
October1st to 15thNight
31%37%21%28%6%
1842
16th to endNight
37%2425%24%6%
2194
November1st to 15thNight
31%25%25%26%8%
2276
16th to endNight
39%27%25%20%4
2340
December1st to 15thNight
50%28%20%14%3
2349
16th to endNight
51%210%20%13%2
2688

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
32%7%35%14%6%3
90
16th to endDay
15%10%46%25%2
96
February1st to 15thDay
20%14%42%17%5%
90
16th to endDay
24%8%35%18%12%
81
March1st to 15thDay
27%10%41%15%5%
90
16th to endDay
18%9%29%29%11%
253
April1st to 15thDay
17%10%29%27%12%2
270
16th to endDay
19%425%28%14%7%
270
May1st to 15thDay
20%9%23%26%11%7%
288
16th to endDay
13%316%28%25%12%
343
June1st to 15thDay
8%216%24%27%20%
495
16th to endDay
5%214%33%29%14%
495
July1st to 15thDay
13%18%28%30%16%
475
16th to endDay
7%15%24%31%29%
458
August1st to 15thDay
9%1325%34%26%
313
16th to endDay
13%6%19%40%19%
332
September1st to 15thDay
11%18%21%30%27%
299
16th to endDay
18%110%19%33%16%
254
October1st to 15thDay
10%218%29%26%12%
227
16th to endDay
15%6%19%32%18%7%
96
November1st to 15thDay
12%5%24%23%24%10%
90
16th to endDay
25%7%31%21%12%2
90
December1st to 15thDay
18%6%42%17%14%
90
16th to endDay
20%11%51%11%5%
96
January1st to 15thNight
25%14%28%25%4
900
16th to endNight
20%12%35%27%3
913
February1st to 15thNight
23%14%34%25%2
704
16th to endNight
22%12%36%26%2
631
March1st to 15thNight
21%11%32%29%5%
720
16th to endNight
19%7%27%33%10%1
637
April1st to 15thNight
15%7%33%29%12%
539
16th to endNight
16%6%26%34%15%
540
May1st to 15thNight
19%5%24%31%15%2
540
16th to endNight
7%213%41%31%3
563
June1st to 15thNight
9%211%39%31%5%
540
16th to endNight
5%29%37%40%5%
540
July1st to 15thNight
9%25%34%42%5%
510
16th to endNight
7%6%30%42%12%
564
August1st to 15thNight
6%5%31%44%11%
539
16th to endNight
8%16%32%43%7%
573
September1st to 15thNight
14%19%27%39%7%
555
16th to endNight
14%313%29%34%5%
657
October1st to 15thNight
14%417%28%28%6%
660
16th to endNight
19%6%22%32%18%1
704
November1st to 15thNight
12%9%25%32%18%2
700
16th to endNight
21%10%26%29%10%
720
December1st to 15thNight
25%11%25%27%9%
729
16th to endNight
26%10%29%27%5%
960
Page generated at 2017-09-13 06:39:13. Version ac04

Copyright 2017 A. Danko


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