Reidland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Reidland clear sky chart from 2005-11-05 to 2017-09-21.

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%
15718
23%
46895
17%
15673
55%
15673
29%
29107

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
31%
900
21%
2506
12%
895
39%
895
23%
1697
January16th to endNight
30%
960
22%
2517
9%
960
39%
960
28%
1703
February1st to 15thNight
28%
707
18%
2115
9%
704
35%
704
21%
1451
February16th to endNight
28%
631
21%
1893
10%
631
37%
631
22%
1263
March1st to 15thNight
30%
720
18%
2160
10%
720
37%
720
22%
1468
March16th to endNight
40%
600
17%
2001
14%
600
45%
600
21%
1321
April1st to 15thNight
42%
539
24%
1797
16%
539
56%
539
33%
1015
April16th to endNight
48%
540
25%
1800
22%
540
55%
540
29%
1070
May1st to 15thNight
48%
539
19%
1656
13%
539
54%
539
27%
1062
May16th to endNight
64%
562
21%
1614
17%
561
66%
561
31%
1011
June1st to 15thNight
71%
540
23%
1440
17%
540
74%
540
41%
861
June16th to endNight
77%
540
24%
1440
19%
540
79%
540
42%
834
July1st to 15thNight
74%
510
18%
1360
16%
510
75%
510
36%
855
July16th to endNight
78%
564
25%
1456
22%
531
79%
531
45%
823
August1st to 15thNight
78%
539
23%
1788
27%
536
79%
536
39%
944
August16th to endNight
76%
573
25%
1910
30%
573
77%
573
36%
1044
September1st to 15thNight
68%
546
28%
1806
29%
546
71%
546
32%
1027
September16th to endNight
64%
681
29%
1881
22%
681
67%
681
36%
1123
October1st to 15thNight
60%
660
32%
1878
25%
660
65%
660
38%
1085
October16th to endNight
49%
704
29%
2170
24%
704
57%
704
33%
1286
November1st to 15thNight
50%
700
32%
2276
27%
700
59%
700
35%
1240
November16th to endNight
39%
720
25%
2340
19%
720
49%
720
27%
1412
December1st to 15thNight
33%
783
18%
2403
11%
783
41%
783
21%
1629
December16th to endNight
31%
960
20%
2688
9%
960
39%
960
21%
1883

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%5%25%5%3445%7%42%
47974
Night
13%5%24424447%46%
47074
TransparencyDay
40%5%11%23%16%3
47658
Night
38%49%24%18%4
46896
SeeingDay
13%316%25%25%15%
5758
Night
16%5%22%31%20%2
15720

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
22%5%36%423346%37%
1432
16th to endDay
14%6%36%5%33445%41%
1704
February1st to 15thDay
15%9%37%5%24346%38%
1746
16th to endDay
15%8%35%5%34346%37%
1580
March1st to 15thDay
20%8%34423445%37%
1800
16th to endDay
16%8%35%5%25%5%47%34%
2230
April1st to 15thDay
12%6%25%423447%44%
2151
16th to endDay
16%6%36%5%2445%6%38%
2160
May1st to 15thDay
16%5%35%5%35%5%5%8%36%
2295
16th to endDay
10%5%26%6%35%6%6%8%38%
2497
June1st to 15thDay
6%3145%35%6%6%9%45%
2520
16th to endDay
43245%36%6%6%11%45%
2520
July1st to 15thDay
8%426%5%45%5%7%9%40%
2520
16th to endDay
42145%46%6%8%12%43%
2611
August1st to 15thDay
6%4345%35%5%5%9%44%
2160
16th to endDay
8%4145%35%6%7%10%42%
2292
September1st to 15thDay
12%4245%345%5%7%43%
2142
16th to endDay
11%5%245%24446%49%
1872
October1st to 15thDay
12%5%24423236%52%
1750
16th to endDay
16%314322335%52%
1700
November1st to 15thDay
13%5%23323345%51%
1582
16th to endDay
19%7%23323235%46%
1620
December1st to 15thDay
20%8%344135%35%37%
1554
16th to endDay
19%9%34424345%36%
1536
January1st to 15thNight
18%7%35%323346%40%
2506
16th to endNight
15%7%35%424345%42%
2517
February1st to 15thNight
17%8%36%6%23435%38%
2106
16th to endNight
15%6%36%5%24445%40%
1893
March1st to 15thNight
17%8%35%42434440%
2160
16th to endNight
15%8%36%424445%39%
2001
April1st to 15thNight
12%423422348%50%
1797
16th to endNight
14%6%1432435%7%46%
1800
May1st to 15thNight
15%6%24424447%42%
1655
16th to endNight
6%426%4345%7%10%43%
1613
June1st to 15thNight
6%4234245%6%9%51%
1440
16th to endNight
3213425%6%8%12%49%
1440
July1st to 15thNight
7%313436%5%6%8%47%
1440
16th to endNight
5%22332435%12%53%
1554
August1st to 15thNight
5%3133345%6%8%54%
1800
16th to endNight
8%31342447%10%49%
1910
September1st to 15thNight
9%42441435%6%52%
1806
16th to endNight
10%425%324346%53%
1881
October1st to 15thNight
10%5%13323346%53%
1878
16th to endNight
17%41342333451%
2170
November1st to 15thNight
13%423312346%54%
2276
16th to endNight
16%6%2432333448%
2340
December1st to 15thNight
21%8%34423445%37%
2403
16th to endNight
22%7%25%5%24335%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
48%36%26%12%1
1433
16th to endDay
44%411%27%10%1
1704
February1st to 15thDay
47%38%25%12%2
1748
16th to endDay
48%311%22%11%2
1580
March1st to 15thDay
49%49%21%12%3
1800
16th to endDay
49%412%23%9%
2232
April1st to 15thDay
40%39%23%20%2
2151
16th to endDay
46%48%26%13%1
2160
May1st to 15thDay
46%6%11%20%14%1
2295
16th to endDay
41%7%15%19%12%2
2501
June1st to 15thDay
32%6%13%25%19%2
2520
16th to endDay
31%7%13%23%19%3
2520
July1st to 15thDay
39%6%12%22%14%5%
2371
16th to endDay
30%7%17%28%14%1
2447
August1st to 15thDay
35%7%13%24%17%1
2148
16th to endDay
34%6%13%23%17%4
2292
September1st to 15thDay
38%6%8%24%18%3
2142
16th to endDay
36%37%22%24%5%
1872
October1st to 15thDay
35%38%24%22%6%
1750
16th to endDay
35%25%29%22%5%
1700
November1st to 15thDay
35%37%20%24%8%
1582
16th to endDay
41%36%27%16%3
1620
December1st to 15thDay
48%311%20%12%2
1554
16th to endDay
49%312%21%11%2
1536
January1st to 15thNight
46%37%23%17%1
2506
16th to endNight
43%410%24%16%1
2517
February1st to 15thNight
49%38%22%13%1
2115
16th to endNight
45%410%23%14%1
1893
March1st to 15thNight
46%5%8%18%15%5%
2160
16th to endNight
46%412%21%13%1
2001
April1st to 15thNight
32%311%26%19%5%
1797
16th to endNight
37%47%26%21%3
1800
May1st to 15thNight
40%5%11%22%17%1
1656
16th to endNight
34%8%12%24%16%3
1615
June1st to 15thNight
28%6%13%26%22%2
1440
16th to endNight
25%8%14%25%19%6%
1440
July1st to 15thNight
33%6%12%25%15%6%
1360
16th to endNight
24%6%15%33%17%1
1456
August1st to 15thNight
26%5%14%27%23%2
1788
16th to endNight
28%6%12%25%20%5%
1910
September1st to 15thNight
33%5%7%28%19%6%
1806
16th to endNight
32%47%23%23%8%
1881
October1st to 15thNight
31%38%21%27%7%
1878
16th to endNight
36%2423%25%6%
2170
November1st to 15thNight
31%26%25%25%9%
2276
16th to endNight
39%27%25%21%3
2340
December1st to 15thNight
48%410%19%15%2
2403
16th to endNight
50%39%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
36%5%33%14%8%1
90
16th to endDay
15%7%45%22%8%
96
February1st to 15thDay
17%11%44%22%4
90
16th to endDay
23%7%35%24%8%
81
March1st to 15thDay
23%5%43%18%7%1
90
16th to endDay
18%9%29%29%11%1
231
April1st to 15thDay
15%10%27%30%14%2
270
16th to endDay
20%323%31%16%5%
270
May1st to 15thDay
20%6%22%27%14%7%
288
16th to endDay
14%218%26%23%14%
397
June1st to 15thDay
9%112%26%31%19%
495
16th to endDay
6%12%33%30%15%
495
July1st to 15thDay
11%29%27%31%17%
475
16th to endDay
5%5%22%36%29%
503
August1st to 15thDay
9%418%39%27%
313
16th to endDay
11%1222%39%21%
332
September1st to 15thDay
12%15%20%33%26%
315
16th to endDay
16%18%19%31%22%
275
October1st to 15thDay
11%118%31%26%12%
190
16th to endDay
14%223%32%19%7%
96
November1st to 15thDay
14%117%33%17%15%
90
16th to endDay
33%424%23%12%2
90
December1st to 15thDay
21%435%21%13%4
90
16th to endDay
23%9%41%20%4
96
January1st to 15thNight
22%12%29%29%6%
900
16th to endNight
19%8%37%30%4
960
February1st to 15thNight
22%10%34%30%3
707
16th to endNight
20%10%35%30%3
631
March1st to 15thNight
21%10%31%31%5%
720
16th to endNight
19%7%26%35%11%
600
April1st to 15thNight
13%7%32%32%11%1
539
16th to endNight
17%425%36%15%
540
May1st to 15thNight
17%422%37%16%1
540
16th to endNight
7%214%40%31%3
563
June1st to 15thNight
8%111%37%37%4
540
16th to endNight
419%40%40%3
540
July1st to 15thNight
9%5%32%45%5%
510
16th to endNight
6%6%25%47%13%
564
August1st to 15thNight
6%6%27%46%11%
539
16th to endNight
10%431%47%6%
573
September1st to 15thNight
11%18%28%41%8%
546
16th to endNight
12%211%30%35%7%
681
October1st to 15thNight
12%317%30%29%6%
660
16th to endNight
19%422%34%18%1
704
November1st to 15thNight
15%5%24%32%21%
700
16th to endNight
21%6%28%30%11%1
720
December1st to 15thNight
26%7%27%28%9%
783
16th to endNight
26%7%29%30%5%
960
Page generated at 2017-09-22 06:35:38. Version ac04

Copyright 2017 A. Danko


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