Algonquin Radio Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Algonquin Radio Observatory clear sky chart from 2005-11-05 to 2017-09-10.

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
26%
14594
12%
46515
7%
14565
33%
14565
15%
33651

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
12%
720
6%
2506
3%
716
16%
716
5%
2075
January16th to endNight
18%
768
11%
2580
6%
768
26%
768
11%
1978
February1st to 15thNight
16%
702
9%
2287
4%
701
23%
701
10%
1780
February16th to endNight
17%
631
11%
2018
5%
631
26%
631
11%
1544
March1st to 15thNight
15%
720
12%
2024
4%
720
23%
720
13%
1560
March16th to endNight
28%
768
19%
2088
8%
768
37%
768
21%
1443
April1st to 15thNight
23%
718
16%
1796
5%
718
29%
718
19%
1340
April16th to endNight
30%
583
17%
1663
9%
583
36%
583
22%
1160
May1st to 15thNight
32%
387
17%
1467
13%
387
42%
387
17%
957
May16th to endNight
32%
374
12%
1497
9%
374
45%
374
18%
939
June1st to 15thNight
32%
360
8%
1428
7%
360
40%
360
17%
927
June16th to endNight
36%
360
10%
1260
8%
360
44%
360
21%
807
July1st to 15thNight
44%
340
15%
1264
17%
340
51%
340
31%
686
July16th to endNight
45%
376
13%
1418
14%
354
51%
354
25%
815
August1st to 15thNight
48%
518
14%
1589
10%
516
52%
516
27%
994
August16th to endNight
46%
640
19%
1786
10%
640
52%
640
34%
1086
September1st to 15thNight
40%
700
15%
1750
7%
700
43%
700
30%
1190
September16th to endNight
41%
657
18%
1823
10%
657
46%
657
29%
1185
October1st to 15thNight
26%
660
15%
1980
9%
660
35%
660
18%
1402
October16th to endNight
21%
704
9%
2145
4%
704
27%
704
11%
1703
November1st to 15thNight
24%
700
14%
2418
11%
700
32%
700
13%
1724
November16th to endNight
19%
720
8%
2520
6%
720
22%
720
8%
2020
December1st to 15thNight
12%
720
6%
2520
2%
720
18%
720
6%
2092
December16th to endNight
11%
768
7%
2688
3%
768
16%
768
6%
2244

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
17%10%47%6%34446%29%
48116
Night
16%11%47%6%3445%6%30%
46681
TransparencyDay
55%410%19%9%1
47801
Night
55%412%18%8%
46515
SeeingDay
23%12%31%20%8%2
5594
Night
23%12%30%23%8%
14597

By Month

Percentage Cloud Cover NE (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
17%16%6%9%7%45%33419%
1432
16th to endDay
13%16%5%11%8%45%5%4421%
1643
February1st to 15thDay
9%15%7%13%10%46%5%35%17%
1575
16th to endDay
15%17%6%9%7%35%435%21%
1455
March1st to 15thDay
15%14%6%10%5%43445%26%
1924
16th to endDay
13%9%47%7%33446%36%
2135
April1st to 15thDay
22%12%45%423335%30%
2152
16th to endDay
21%9%35%423235%37%
2307
May1st to 15thDay
20%9%37%5%34346%31%
2482
16th to endDay
16%7%46%5%34446%35%
2618
June1st to 15thDay
21%8%36%6%35%45%7%27%
2526
16th to endDay
17%6%25%6%35%5%6%8%31%
2700
July1st to 15thDay
14%5%25%5%45%5%5%7%36%
2616
16th to endDay
13%6%36%5%26%6%6%9%33%
2654
August1st to 15thDay
15%6%36%6%46%5%5%7%32%
2358
16th to endDay
14%5%26%7%45%6%6%7%33%
2403
September1st to 15thDay
18%7%25%5%345%47%34%
2098
16th to endDay
19%7%25%424337%38%
1806
October1st to 15thDay
21%10%36%5%43336%30%
1650
16th to endDay
28%13%46%5%34335%19%
1727
November1st to 15thDay
18%11%37%5%35%5%5%5%29%
1439
16th to endDay
21%17%8%9%6%3434317%
1440
December1st to 15thDay
18%18%7%11%8%35%44312%
1440
16th to endDay
19%19%8%11%6%3333415%
1536
January1st to 15thNight
14%15%8%12%9%45%45%5%13%
2506
16th to endNight
11%15%6%11%7%45%5%5%6%21%
2580
February1st to 15thNight
10%13%6%11%9%46%5%5%6%20%
2285
16th to endNight
15%14%5%10%8%35%34424%
2018
March1st to 15thNight
15%13%6%8%7%35%34427%
2012
16th to endNight
13%8%47%6%24335%39%
2088
April1st to 15thNight
20%11%35%5%2334434%
1796
16th to endNight
18%9%26%6%24346%35%
1663
May1st to 15thNight
18%10%25%5%24446%35%
1467
16th to endNight
15%5%45%5%345%5%6%38%
1495
June1st to 15thNight
16%7%36%5%2446%8%34%
1428
16th to endNight
15%435%5%345%7%8%35%
1260
July1st to 15thNight
10%425%42446%8%47%
1340
16th to endNight
9%423435%5%6%8%44%
1514
August1st to 15thNight
11%5%25%5%245%7%7%42%
1599
16th to endNight
9%425%5%2446%9%46%
1786
September1st to 15thNight
15%6%26%5%24347%41%
1750
16th to endNight
17%5%24414346%44%
1823
October1st to 15thNight
20%10%45%423335%35%
1980
16th to endNight
25%11%46%6%3445%5%21%
2145
November1st to 15thNight
16%12%45%6%3446%430%
2418
16th to endNight
22%15%6%10%6%3433420%
2520
December1st to 15thNight
19%19%6%9%7%35%34416%
2520
16th to endNight
21%17%6%11%7%3434414%
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
68%48%11%6%
1433
16th to endDay
65%48%13%6%1
1643
February1st to 15thDay
68%39%12%5%
1577
16th to endDay
65%36%14%9%
1455
March1st to 15thDay
61%310%16%7%1
1935
16th to endDay
49%28%19%15%3
2135
April1st to 15thDay
56%37%18%11%2
2152
16th to endDay
50%26%22%15%2
2307
May1st to 15thDay
54%39%17%12%2
2482
16th to endDay
49%49%22%11%2
2622
June1st to 15thDay
55%410%19%9%
2526
16th to endDay
48%6%12%21%10%1
2700
July1st to 15thDay
43%5%12%26%11%1
2464
16th to endDay
46%5%13%24%8%
2487
August1st to 15thDay
49%5%14%20%9%
2344
16th to endDay
46%5%15%25%7%
2403
September1st to 15thDay
48%413%23%9%
2098
16th to endDay
48%5%12%27%6%
1806
October1st to 15thDay
56%311%18%9%
1650
16th to endDay
68%410%11%4
1727
November1st to 15thDay
56%5%13%17%6%
1439
16th to endDay
71%39%10%31
1440
December1st to 15thDay
74%39%10%1
1440
16th to endDay
72%38%11%4
1536
January1st to 15thNight
72%49%9%4
2506
16th to endNight
62%49%15%7%
2580
February1st to 15thNight
63%412%14%5%
2287
16th to endNight
62%38%17%7%
2018
March1st to 15thNight
59%410%17%7%
2024
16th to endNight
48%210%18%16%2
2088
April1st to 15thNight
54%26%20%13%1
1796
16th to endNight
49%28%20%14%2
1663
May1st to 15thNight
48%49%19%15%2
1467
16th to endNight
44%413%22%12%2
1497
June1st to 15thNight
46%5%13%22%10%
1428
16th to endNight
43%6%14%23%11%1
1260
July1st to 15thNight
32%415%28%17%1
1264
16th to endNight
36%5%18%28%10%
1418
August1st to 15thNight
37%7%18%24%11%
1589
16th to endNight
34%420%31%9%
1786
September1st to 15thNight
42%417%24%10%
1750
16th to endNight
41%415%31%7%
1823
October1st to 15thNight
52%311%21%10%
1980
16th to endNight
63%5%11%13%5%
2145
November1st to 15thNight
54%5%14%16%8%
2418
16th to endNight
68%311%12%2
2520
December1st to 15thNight
71%410%10%3
2520
16th to endNight
73%38%9%4
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
25%20%38%11%5%
60
16th to endDay
36%8%34%17%3
82
February1st to 15thDay
28%18%36%14%1
90
16th to endDay
37%17%32%9%2
114
March1st to 15thDay
29%17%31%17%4
270
16th to endDay
20%19%31%19%7%2
288
April1st to 15thDay
25%18%31%17%42
270
16th to endDay
27%14%30%14%9%3
270
May1st to 15thDay
36%9%23%17%9%4
288
16th to endDay
22%15%33%18%8%1
331
June1st to 15thDay
28%10%32%19%8%
321
16th to endDay
20%12%32%22%10%1
495
July1st to 15thDay
15%9%34%29%8%2
398
16th to endDay
11%8%32%30%13%3
326
August1st to 15thDay
17%430%29%12%6%
313
16th to endDay
17%7%29%27%12%6%
332
September1st to 15thDay
22%8%27%19%13%7%
294
16th to endDay
21%8%27%25%11%5%
254
October1st to 15thDay
24%13%30%19%9%2
255
16th to endDay
36%10%32%15%5%
266
November1st to 15thDay
19%16%40%17%5%1
93
16th to endDay
40%15%28%15%1
60
December1st to 15thDay
26%21%35%11%5%
60
16th to endDay
34%26%29%7%1
64
January1st to 15thNight
23%19%34%18%5%
720
16th to endNight
19%13%38%20%7%
768
February1st to 15thNight
17%19%37%19%5%
704
16th to endNight
24%17%34%20%3
631
March1st to 15thNight
24%20%32%18%3
720
16th to endNight
19%15%30%23%10%1
768
April1st to 15thNight
27%16%29%22%4
718
16th to endNight
24%10%29%24%9%
583
May1st to 15thNight
23%8%28%28%9%1
387
16th to endNight
16%10%34%26%11%
375
June1st to 15thNight
20%8%31%30%8%
360
16th to endNight
16%7%30%35%8%
360
July1st to 15thNight
12%433%34%13%
340
16th to endNight
9%434%33%17%
376
August1st to 15thNight
15%422%32%22%2
518
16th to endNight
12%5%30%34%14%2
640
September1st to 15thNight
19%6%29%26%15%2
700
16th to endNight
21%6%25%28%16%2
657
October1st to 15thNight
28%11%28%22%8%1
660
16th to endNight
33%13%25%20%6%
704
November1st to 15thNight
25%15%27%22%9%
700
16th to endNight
30%16%26%20%6%
720
December1st to 15thNight
29%17%33%14%4
720
16th to endNight
34%14%28%17%31
768
Page generated at 2017-09-11 19:35:23. Version ac04

Copyright 2017 A. Danko


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