Taylor Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taylor Observatory 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
62%
15238
28%
46861
23%
15201
67%
15201
38%
25452

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
53%
717
18%
2395
16%
716
57%
716
23%
1499
January16th to endNight
51%
768
26%
2496
24%
768
57%
768
28%
1524
February1st to 15thNight
48%
700
22%
2288
20%
700
55%
700
21%
1494
February16th to endNight
46%
632
23%
1942
17%
632
53%
632
26%
1207
March1st to 15thNight
47%
720
14%
1985
10%
720
51%
720
23%
1376
March16th to endNight
44%
768
20%
2106
13%
768
49%
768
26%
1378
April1st to 15thNight
41%
719
22%
1799
9%
719
49%
719
27%
1188
April16th to endNight
52%
720
25%
1800
11%
720
58%
720
43%
1040
May1st to 15thNight
60%
545
30%
1625
19%
545
67%
545
51%
797
May16th to endNight
65%
390
28%
1513
26%
390
74%
390
45%
622
June1st to 15thNight
65%
360
27%
1440
29%
360
75%
360
42%
617
June16th to endNight
76%
360
35%
1440
44%
360
83%
360
61%
500
July1st to 15thNight
89%
368
34%
1388
43%
368
91%
368
77%
442
July16th to endNight
92%
564
40%
1593
37%
531
94%
531
83%
596
August1st to 15thNight
91%
538
40%
1611
33%
535
92%
535
78%
624
August16th to endNight
89%
735
44%
1881
29%
735
91%
735
80%
829
September1st to 15thNight
90%
706
43%
1765
29%
706
92%
706
84%
769
September16th to endNight
80%
656
42%
1816
35%
656
85%
656
70%
793
October1st to 15thNight
69%
660
32%
1980
29%
660
77%
660
48%
979
October16th to endNight
68%
704
32%
2112
32%
704
73%
704
41%
1134
November1st to 15thNight
62%
700
24%
2179
22%
700
68%
700
34%
1233
November16th to endNight
55%
720
22%
2499
21%
720
60%
720
27%
1438
December1st to 15thNight
47%
720
20%
2520
16%
720
54%
720
20%
1623
December16th to endNight
43%
768
20%
2688
17%
768
50%
768
20%
1750

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
7%413313345%61%
47809
Night
8%413323346%57%
47047
TransparencyDay
25%47%19%24%17%
47495
Night
27%48%18%23%17%
46862
SeeingDay
10%13%24%29%17%5%
5970
Night
10%7%15%28%30%8%
15247

By Month

Percentage Cloud Cover SW (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
15%7%35%5%23335%42%
1543
16th to endDay
15%6%35%423446%42%
1728
February1st to 15thDay
15%8%2442345%6%42%
1576
16th to endDay
19%6%245%2346%7%38%
1532
March1st to 15thDay
16%9%37%5%2445%6%33%
1974
16th to endDay
14%6%26%6%3445%7%38%
2118
April1st to 15thDay
13%8%345%34447%41%
2149
16th to endDay
5%42442345%7%56%
2160
May1st to 15thDay
3312213348%64%
2324
16th to endDay
5%31332336%7%59%
2599
June1st to 15thDay
3313313336%64%
2520
16th to endDay
2111113480%
2520
July1st to 15thDay
111112386%
2487
16th to endDay
1111387%
2468
August1st to 15thDay
11122384%
2340
16th to endDay
111388%
2321
September1st to 15thDay
111122483%
2114
16th to endDay
21212235%77%
1812
October1st to 15thDay
7%312222335%64%
1650
16th to endDay
10%312423246%58%
1760
November1st to 15thDay
8%4144245%48%51%
1678
16th to endDay
13%6%34434345%47%
1460
December1st to 15thDay
16%8%45%414435%41%
1440
16th to endDay
20%8%3432345%5%37%
1536
January1st to 15thNight
15%5%245%2445%8%41%
2395
16th to endNight
16%6%24313336%46%
2496
February1st to 15thNight
13%6%26%5%345%5%5%39%
2276
16th to endNight
15%5%245%25%45%7%42%
1942
March1st to 15thNight
14%6%36%5%3445%8%36%
1985
16th to endNight
12%7%25%324446%43%
2106
April1st to 15thNight
10%5%26%5%25%45%7%45%
1799
16th to endNight
5%323324347%59%
1800
May1st to 15thNight
2212323346%67%
1625
16th to endNight
2112313347%66%
1512
June1st to 15thNight
4312213336%67%
1440
16th to endNight
21211112381%
1440
July1st to 15thNight
11112287%
1470
16th to endNight
111387%
1701
August1st to 15thNight
111112386%
1620
16th to endNight
11112484%
1881
September1st to 15thNight
1122386%
1765
16th to endNight
111112346%75%
1816
October1st to 15thNight
5%213222246%66%
1980
16th to endNight
8%21232345%7%57%
2112
November1st to 15thNight
8%4133345%7%8%49%
2179
16th to endNight
10%5%245%2335%6%48%
2499
December1st to 15thNight
17%6%25%5%23446%40%
2520
16th to endNight
19%7%25%424446%38%
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
44%49%16%14%11%
1543
16th to endDay
42%47%13%19%12%
1728
February1st to 15thDay
43%47%17%21%5%
1576
16th to endDay
43%6%10%22%12%4
1532
March1st to 15thDay
50%5%9%15%12%6%
1974
16th to endDay
45%6%11%17%15%3
2118
April1st to 15thDay
43%5%12%19%15%2
2149
16th to endDay
26%5%12%26%20%7%
2160
May1st to 15thDay
19%49%30%28%7%
2324
16th to endDay
23%5%11%32%21%6%
2603
June1st to 15thDay
21%410%24%24%14%
2520
16th to endDay
9%1418%37%27%
2520
July1st to 15thDay
5%1211%34%42%
2340
16th to endDay
6%2310%27%50%
2313
August1st to 15thDay
6%1317%35%35%
2324
16th to endDay
41315%38%36%
2321
September1st to 15thDay
7%2314%36%36%
2114
16th to endDay
11%35%22%34%24%
1812
October1st to 15thDay
22%37%22%27%17%
1650
16th to endDay
27%47%21%26%12%
1760
November1st to 15thDay
30%6%11%28%14%9%
1678
16th to endDay
39%5%8%19%18%8%
1460
December1st to 15thDay
46%5%6%15%20%5%
1440
16th to endDay
47%48%14%16%8%
1536
January1st to 15thNight
41%5%10%17%16%9%
2395
16th to endNight
39%37%15%18%14%
2496
February1st to 15thNight
43%6%7%16%18%7%
2288
16th to endNight
38%5%12%24%16%3
1942
March1st to 15thNight
43%8%12%14%14%6%
1985
16th to endNight
40%5%11%19%17%5%
2106
April1st to 15thNight
36%7%14%21%15%4
1799
16th to endNight
25%411%28%23%6%
1800
May1st to 15thNight
18%36%26%33%10%
1626
16th to endNight
15%5%14%33%23%8%
1513
June1st to 15thNight
17%5%10%23%25%16%
1440
16th to endNight
10%2416%34%31%
1440
July1st to 15thNight
6%128%35%47%
1388
16th to endNight
5%1410%20%58%
1593
August1st to 15thNight
7%1211%33%43%
1611
16th to endNight
5%2312%36%39%
1881
September1st to 15thNight
5%1311%34%43%
1765
16th to endNight
9%2422%32%28%
1816
October1st to 15thNight
20%37%20%28%18%
1980
16th to endNight
24%5%7%21%23%17%
2112
November1st to 15thNight
29%6%15%24%14%9%
2179
16th to endNight
35%49%19%21%9%
2499
December1st to 15thNight
44%5%7%14%20%6%
2520
16th to endNight
45%48%15%18%7%
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%15%24%12%15%
171
16th to endDay
17%17%25%21%14%3
256
February1st to 15thDay
22%17%23%21%13%2
236
16th to endDay
20%19%23%23%11%
230
March1st to 15thDay
26%21%21%16%10%3
270
16th to endDay
16%23%31%19%7%
288
April1st to 15thDay
21%25%23%18%8%2
269
16th to endDay
12%26%28%20%10%1
270
May1st to 15thDay
8%22%34%20%11%2
288
16th to endDay
8%15%22%27%19%6%
330
June1st to 15thDay
6%16%29%33%10%3
315
16th to endDay
27%31%31%20%5%
315
July1st to 15thDay
2219%42%25%7%
305
16th to endDay
115%49%21%11%
327
August1st to 15thDay
1121%42%24%8%
315
16th to endDay
1220%36%27%12%
332
September1st to 15thDay
219%44%27%7%
300
16th to endDay
46%21%34%24%8%
255
October1st to 15thDay
9%12%23%30%16%8%
255
16th to endDay
12%13%23%27%20%1
272
November1st to 15thDay
8%13%18%26%27%6%
184
16th to endDay
14%19%34%15%14%1
63
December1st to 15thDay
33%16%33%11%31
60
16th to endDay
15%21%20%18%18%4
64
January1st to 15thNight
16%8%12%31%23%7%
720
16th to endNight
20%7%16%28%20%7%
768
February1st to 15thNight
16%9%17%30%22%3
704
16th to endNight
17%11%19%27%19%4
632
March1st to 15thNight
17%10%17%27%22%4
720
16th to endNight
15%13%22%26%18%4
768
April1st to 15thNight
11%15%25%25%18%3
719
16th to endNight
6%14%22%27%22%5%
720
May1st to 15thNight
36%25%30%28%6%
546
16th to endNight
37%19%30%34%4
391
June1st to 15thNight
5%6%19%31%34%3
360
16th to endNight
2215%38%36%3
360
July1st to 15thNight
17%26%53%10%
368
16th to endNight
1422%53%17%
564
August1st to 15thNight
1428%47%18%
538
16th to endNight
7%25%52%13%
735
September1st to 15thNight
15%27%49%15%
706
16th to endNight
2310%28%37%16%
656
October1st to 15thNight
6%5%12%29%33%12%
660
16th to endNight
8%5%13%25%32%13%
704
November1st to 15thNight
9%6%14%30%29%8%
700
16th to endNight
11%10%14%30%24%8%
720
December1st to 15thNight
20%10%13%28%18%7%
720
16th to endNight
20%12%17%28%18%2
768
Page generated at 2017-09-13 04:39:21. Version ac04

Copyright 2017 A. Danko


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