Mole Hill Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mole Hill Observatory clear sky chart from 2005-11-05 to 2018-11-30.

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
60%
16841
22%
51754
18%
16798
64%
16798
29%
31696

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
41%
972
22%
2522
11%
970
47%
970
27%
1726
January16th to endNight
44%
1004
22%
2668
10%
1004
49%
1004
28%
1778
February1st to 15thNight
44%
764
22%
2291
14%
759
49%
759
24%
1481
February16th to endNight
44%
609
23%
1975
13%
609
50%
609
25%
1211
March1st to 15thNight
45%
585
22%
2145
17%
585
52%
585
22%
1332
March16th to endNight
55%
624
22%
2288
20%
624
60%
624
27%
1278
April1st to 15thNight
51%
584
21%
2142
17%
584
58%
584
24%
1267
April16th to endNight
50%
579
21%
1967
19%
579
56%
579
25%
1216
May1st to 15thNight
59%
584
22%
1800
21%
584
62%
584
29%
1104
May16th to endNight
69%
609
22%
1828
25%
609
71%
609
33%
1096
June1st to 15thNight
82%
585
21%
1755
26%
585
82%
585
40%
962
June16th to endNight
76%
585
13%
1755
16%
585
76%
585
31%
1082
July1st to 15thNight
81%
555
15%
1665
18%
555
81%
555
31%
1013
July16th to endNight
85%
612
19%
1738
24%
579
86%
579
40%
973
August1st to 15thNight
90%
575
24%
1717
27%
572
90%
572
47%
882
August16th to endNight
81%
621
16%
2213
20%
621
81%
621
31%
1258
September1st to 15thNight
74%
585
15%
2145
18%
585
75%
585
23%
1358
September16th to endNight
72%
582
22%
2145
26%
582
73%
582
24%
1325
October1st to 15thNight
79%
650
31%
2210
29%
650
80%
650
38%
1166
October16th to endNight
71%
832
32%
2496
25%
832
73%
832
42%
1360
November1st to 15thNight
63%
820
24%
2460
20%
820
65%
820
31%
1526
November16th to endNight
57%
910
29%
2590
19%
910
63%
910
34%
1569
December1st to 15thNight
45%
975
23%
2535
14%
975
48%
975
25%
1782
December16th to endNight
40%
1040
18%
2704
8%
1040
44%
1040
21%
1951

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
11%5%25%5%35%5%6%9%39%
52535
Night
11%5%2442445%8%45%
51951
TransparencyDay
36%7%15%21%12%5%
52235
Night
35%6%14%21%14%7%
51756
SeeingDay
11%19%24%36%16%
6766
Night
14%314%29%31%7%
16847

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%24424445%37%
1746
16th to endDay
17%7%25%4235%45%40%
1918
February1st to 15thDay
19%7%34423235%43%
1900
16th to endDay
16%7%26%42345%6%40%
1782
March1st to 15thDay
19%7%34423447%38%
2145
16th to endDay
11%5%25%32435%7%47%
2286
April1st to 15thDay
12%6%3342445%9%42%
2136
16th to endDay
13%5%35%5%24447%42%
2266
May1st to 15thDay
10%6%35%5%35%47%9%38%
2477
16th to endDay
6%425%5%46%6%7%12%37%
2638
June1st to 15thDay
33135%36%7%9%13%41%
2535
16th to endDay
8%435%6%47%8%10%12%28%
2535
July1st to 15thDay
8%5%245%36%7%9%11%33%
2535
16th to endDay
6%3245%46%6%10%13%36%
2674
August1st to 15thDay
22235%25%7%8%14%44%
2486
16th to endDay
8%426%5%46%7%9%13%32%
2334
September1st to 15thDay
10%7%26%6%46%6%7%9%30%
2145
16th to endDay
9%6%25%6%35%6%8%9%34%
2145
October1st to 15thDay
6%413435%5%6%10%48%
2065
16th to endDay
10%5%15%323345%53%
2080
November1st to 15thDay
10%5%35%6%35%6%5%8%40%
2058
16th to endDay
14%424434346%47%
2022
December1st to 15thDay
21%8%35%433347%35%
1755
16th to endDay
18%8%36%5%34446%35%
1872
January1st to 15thNight
18%6%34423336%43%
2522
16th to endNight
17%6%3442345%6%42%
2668
February1st to 15thNight
17%7%34324345%44%
2282
16th to endNight
12%6%244245%5%6%44%
1975
March1st to 15thNight
16%6%35%424437%41%
2145
16th to endNight
10%5%2432335%7%50%
2288
April1st to 15thNight
12%6%245%2345%8%42%
2142
16th to endNight
13%6%24425%45%8%41%
1967
May1st to 15thNight
9%5%25%435%47%9%42%
1799
16th to endNight
6%424435%6%7%12%42%
1827
June1st to 15thNight
43133245%6%12%51%
1755
16th to endNight
6%4245%26%6%8%14%37%
1755
July1st to 15thNight
4424435%6%7%14%42%
1755
16th to endNight
32233336%7%14%48%
1846
August1st to 15thNight
123235%7%14%56%
1727
16th to endNight
6%3134245%8%12%46%
2213
September1st to 15thNight
7%426%5%35%5%7%11%40%
2145
16th to endNight
8%5%26%5%35%5%6%9%42%
2145
October1st to 15thNight
5%31332445%8%57%
2210
16th to endNight
9%313322336%60%
2496
November1st to 15thNight
11%5%25%334348%47%
2460
16th to endNight
11%5%14324336%52%
2590
December1st to 15thNight
20%6%2442335%5%39%
2535
16th to endNight
18%8%36%424445%36%
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
46%6%7%15%15%8%
1747
16th to endDay
44%5%6%16%16%10%
1918
February1st to 15thDay
45%48%15%15%11%
1901
16th to endDay
42%6%10%17%15%7%
1782
March1st to 15thDay
44%5%11%15%15%6%
2145
16th to endDay
35%7%13%16%18%8%
2288
April1st to 15thDay
37%7%13%19%15%8%
2136
16th to endDay
39%6%10%24%11%7%
2266
May1st to 15thDay
36%8%15%22%10%6%
2477
16th to endDay
30%8%18%25%15%1
2642
June1st to 15thDay
24%8%19%29%16%
2535
16th to endDay
36%10%20%25%6%
2535
July1st to 15thDay
34%11%25%22%6%
2396
16th to endDay
28%11%27%29%2
2519
August1st to 15thDay
21%11%28%32%6%
2472
16th to endDay
35%12%23%22%5%
2334
September1st to 15thDay
42%12%16%19%7%1
2145
16th to endDay
38%9%15%19%13%4
2145
October1st to 15thDay
27%6%13%27%18%7%
2065
16th to endDay
32%39%17%22%14%
2080
November1st to 15thDay
39%7%12%18%14%7%
2058
16th to endDay
37%410%17%18%11%
2022
December1st to 15thDay
49%5%8%14%14%6%
1755
16th to endDay
50%5%9%14%12%6%
1872
January1st to 15thNight
44%46%14%19%9%
2522
16th to endNight
42%46%17%17%11%
2668
February1st to 15thNight
42%5%10%11%16%13%
2292
16th to endNight
39%5%8%17%20%8%
1975
March1st to 15thNight
42%5%11%15%15%9%
2145
16th to endNight
34%412%16%20%10%
2288
April1st to 15thNight
38%5%11%17%17%9%
2142
16th to endNight
40%5%12%20%12%8%
1967
May1st to 15thNight
35%7%15%20%12%8%
1800
16th to endNight
31%8%17%25%15%1
1829
June1st to 15thNight
25%6%16%31%18%1
1755
16th to endNight
33%9%21%27%7%
1755
July1st to 15thNight
30%10%24%27%6%
1665
16th to endNight
23%9%31%31%3
1738
August1st to 15thNight
16%9%28%39%5%
1717
16th to endNight
28%10%27%26%6%
2213
September1st to 15thNight
36%11%20%18%10%2
2145
16th to endNight
37%9%13%22%13%4
2145
October1st to 15thNight
24%7%12%26%18%9%
2210
16th to endNight
26%47%18%25%17%
2496
November1st to 15thNight
36%6%14%20%15%6%
2460
16th to endNight
34%48%19%19%12%
2590
December1st to 15thNight
45%6%8%16%15%7%
2535
16th to endNight
48%6%7%16%12%9%
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%120%34%21%
135
16th to endDay
18%426%32%16%
144
February1st to 15thDay
25%5%19%31%16%2
135
16th to endDay
10%330%41%14%
120
March1st to 15thDay
24%222%38%11%
135
16th to endDay
14%20%45%18%
144
April1st to 15thDay
13%228%31%22%2
135
16th to endDay
14%220%39%22%1
278
May1st to 15thDay
10%219%45%19%1
494
16th to endDay
9%113%38%32%4
597
June1st to 15thDay
4326%53%11%
570
16th to endDay
10%418%48%18%
570
July1st to 15thDay
7%1212%49%27%
550
16th to endDay
6%116%52%31%
595
August1st to 15thDay
218%50%38%
549
16th to endDay
11%18%34%43%
246
September1st to 15thDay
16%112%36%33%
180
16th to endDay
6%17%48%35%
180
October1st to 15thDay
5%119%41%31%
180
16th to endDay
25%19%21%33%8%
192
November1st to 15thDay
20%211%28%31%5%
180
16th to endDay
19%316%30%18%10%
178
December1st to 15thDay
33%16%23%21%5%
135
16th to endDay
30%417%29%16%1
144
January1st to 15thNight
21%5%23%31%16%1
975
16th to endNight
19%6%24%36%13%
1004
February1st to 15thNight
22%7%20%34%15%
764
16th to endNight
15%7%25%40%10%
609
March1st to 15thNight
19%5%21%39%13%
585
16th to endNight
13%419%42%17%1
624
April1st to 15thNight
15%322%43%15%
584
16th to endNight
17%221%38%19%
579
May1st to 15thNight
12%217%50%16%
585
16th to endNight
6%113%39%36%3
611
June1st to 15thNight
41327%57%5%
585
16th to endNight
7%1420%51%13%
585
July1st to 15thNight
5%213%52%24%
555
16th to endNight
3111%54%28%
612
August1st to 15thNight
15%62%29%
575
16th to endNight
7%18%53%28%
621
September1st to 15thNight
10%210%51%24%
585
16th to endNight
9%1418%47%17%
582
October1st to 15thNight
6%5%23%50%13%
650
16th to endNight
11%210%33%35%7%
832
November1st to 15thNight
14%312%29%35%5%
820
16th to endNight
14%318%34%25%3
910
December1st to 15thNight
24%418%27%21%2
975
16th to endNight
24%6%21%29%15%1
1040
Page generated at 2018-12-01 10:35:35. Version ac04

Copyright 2018 A. Danko


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