Mark Ice Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mark Ice Station clear sky chart from 2005-11-05 to 2017-12-01.

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
24%
15149
17%
47752
7%
15117
36%
15117
18%
31271

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
19%
2506
5%
716
30%
716
13%
1646
January16th to endNight
11%
768
18%
2688
3%
768
31%
768
13%
1736
February1st to 15thNight
9%
704
15%
2214
2%
701
25%
701
13%
1498
February16th to endNight
13%
631
20%
1893
5%
631
32%
631
15%
1265
March1st to 15thNight
15%
720
16%
2160
5%
720
29%
720
15%
1472
March16th to endNight
20%
768
22%
2017
6%
768
32%
768
20%
1354
April1st to 15thNight
18%
718
17%
1796
3%
718
26%
718
20%
1265
April16th to endNight
22%
603
17%
1683
3%
603
32%
603
19%
1147
May1st to 15thNight
21%
540
15%
1620
5%
540
31%
540
16%
1134
May16th to endNight
29%
375
11%
1497
8%
374
39%
374
13%
1006
June1st to 15thNight
27%
360
11%
1440
6%
360
40%
360
14%
958
June16th to endNight
36%
360
10%
1440
9%
360
44%
360
18%
915
July1st to 15thNight
44%
340
12%
1360
15%
340
49%
340
22%
833
July16th to endNight
47%
376
15%
1418
14%
354
55%
354
24%
832
August1st to 15thNight
40%
471
16%
1542
10%
469
46%
469
24%
940
August16th to endNight
46%
738
20%
1884
10%
738
50%
738
31%
1225
September1st to 15thNight
36%
720
20%
1844
8%
720
43%
720
33%
1185
September16th to endNight
42%
717
26%
1980
16%
717
50%
717
33%
1198
October1st to 15thNight
31%
720
21%
2031
10%
720
43%
720
23%
1335
October16th to endNight
22%
768
16%
2489
5%
768
35%
768
16%
1654
November1st to 15thNight
26%
760
19%
2472
9%
760
39%
760
19%
1589
November16th to endNight
22%
780
21%
2558
8%
780
38%
780
18%
1612
December1st to 15thNight
16%
724
16%
2532
4%
724
31%
724
14%
1675
December16th to endNight
12%
768
17%
2688
4%
768
28%
768
12%
1797

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
16%6%35%5%35%45%7%36%
48676
Night
15%6%35%42445%6%40%
47922
Cloud CoverDay
16%6%35%5%3445%6%37%
48686
Night
15%6%25%42445%6%40%
47927
TransparencyDay
45%6%12%20%13%1
48364
Night
42%6%12%21%14%1
47752
SeeingDay
21%16%30%19%8%2
6071
Night
21%16%32%21%6%
15149

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
13%7%37%435%6%6%6%35%
1432
16th to endDay
12%7%245%245%7%7%38%
1536
February1st to 15thDay
15%6%36%6%47%5%6%7%30%
1644
16th to endDay
13%9%47%6%34446%36%
1580
March1st to 15thDay
17%9%27%435%45%6%33%
1790
16th to endDay
16%6%35%5%24346%40%
2202
April1st to 15thDay
15%8%35%6%35%345%36%
2152
16th to endDay
17%6%35%5%2445%6%38%
2276
May1st to 15thDay
23%7%36%6%34445%30%
2342
16th to endDay
18%5%35%5%34447%36%
2618
June1st to 15thDay
24%5%25%5%24448%30%
2520
16th to endDay
16%6%36%5%45%5%6%8%31%
2520
July1st to 15thDay
13%426%6%46%5%6%8%34%
2520
16th to endDay
13%5%26%5%46%46%8%35%
2654
August1st to 15thDay
13%5%26%6%46%6%6%8%34%
2394
16th to endDay
10%425%5%35%5%6%8%41%
2315
September1st to 15thDay
13%5%25%5%345%47%42%
2115
16th to endDay
13%6%24322336%50%
1980
October1st to 15thDay
18%7%25%5%24335%39%
1929
16th to endDay
16%6%35%5%35%446%38%
1734
November1st to 15thDay
16%6%345%23346%42%
1716
16th to endDay
17%6%245%24435%43%
1729
December1st to 15thDay
16%6%37%6%34346%36%
1442
16th to endDay
19%9%35%6%25%45%6%31%
1536
January1st to 15thNight
13%7%36%425%45%7%38%
2506
16th to endNight
12%8%36%5%345%46%38%
2688
February1st to 15thNight
12%9%36%5%35%5%5%6%36%
2213
16th to endNight
13%8%45%426%5%46%38%
1893
March1st to 15thNight
16%7%35%435%5%46%37%
2147
16th to endNight
14%6%25%325%45%6%42%
2017
April1st to 15thNight
15%8%36%5%2445%5%38%
1796
16th to endNight
19%6%25%423346%39%
1683
May1st to 15thNight
19%8%26%4345%46%34%
1620
16th to endNight
17%6%27%6%2446%8%33%
1495
June1st to 15thNight
24%6%34424437%35%
1440
16th to endNight
15%5%35%3345%5%8%39%
1440
July1st to 15thNight
11%5%25%425%5%7%7%41%
1440
16th to endNight
12%414425%5%6%9%43%
1514
August1st to 15thNight
8%6%27%5%2446%7%44%
1552
16th to endNight
12%5%2443436%8%46%
1884
September1st to 15thNight
13%5%1432345%5%49%
1844
16th to endNight
11%415%323446%52%
1980
October1st to 15thNight
18%5%25%413445%43%
2031
16th to endNight
19%6%345%25%46%6%37%
2489
November1st to 15thNight
15%7%35%424335%43%
2472
16th to endNight
15%6%244345%46%42%
2558
December1st to 15thNight
17%7%36%424446%38%
2532
16th to endNight
17%8%36%4245%5%7%33%
2688

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
13%8%35%5%35%5%5%7%36%
1432
16th to endDay
12%7%245%245%6%7%39%
1536
February1st to 15thDay
15%6%26%6%47%6%5%6%30%
1644
16th to endDay
14%8%46%6%34446%36%
1580
March1st to 15thDay
17%9%35%5%3435%6%34%
1800
16th to endDay
16%6%35%5%24346%41%
2202
April1st to 15thDay
16%7%46%5%44345%37%
2152
16th to endDay
17%6%25%5%2445%6%38%
2276
May1st to 15thDay
24%7%36%5%34445%31%
2342
16th to endDay
18%5%35%5%24447%36%
2618
June1st to 15thDay
25%6%2443445%7%31%
2520
16th to endDay
17%5%27%5%36%47%8%31%
2520
July1st to 15thDay
14%436%6%36%5%6%8%35%
2520
16th to endDay
13%436%6%36%5%6%7%35%
2654
August1st to 15thDay
14%435%7%36%5%7%8%35%
2394
16th to endDay
11%4245%35%5%6%8%41%
2315
September1st to 15thDay
14%5%25%5%35%446%42%
2115
16th to endDay
14%5%14422336%51%
1980
October1st to 15thDay
19%6%25%5%34345%40%
1929
16th to endDay
17%5%25%6%24445%39%
1734
November1st to 15thDay
16%7%35%42335%6%42%
1716
16th to endDay
17%6%25%5%24435%43%
1729
December1st to 15thDay
17%6%26%5%44445%37%
1442
16th to endDay
20%8%35%425%35%6%31%
1536
January1st to 15thNight
13%7%35%435%45%5%40%
2506
16th to endNight
13%9%35%5%345%46%38%
2688
February1st to 15thNight
12%9%45%5%345%5%6%36%
2206
16th to endNight
14%8%35%42445%439%
1893
March1st to 15thNight
17%7%34425%5%6%5%37%
2160
16th to endNight
15%6%34325%5%5%6%43%
2016
April1st to 15thNight
16%7%35%5%2446%5%38%
1796
16th to endNight
20%6%24423346%40%
1683
May1st to 15thNight
20%7%25%5%2445%6%35%
1620
16th to endNight
19%5%27%6%2445%8%33%
1495
June1st to 15thNight
24%6%24424347%35%
1440
16th to endNight
16%5%25%43345%8%40%
1440
July1st to 15thNight
13%425%425%5%5%8%41%
1440
16th to endNight
12%4135%35%46%10%42%
1514
August1st to 15thNight
8%5%36%42446%8%44%
1552
16th to endNight
13%5%1442346%8%45%
1884
September1st to 15thNight
14%423323446%49%
1844
16th to endNight
12%424323346%52%
1980
October1st to 15thNight
18%6%245%23346%43%
2031
16th to endNight
19%6%2432445%6%38%
2489
November1st to 15thNight
15%7%25%433345%43%
2472
16th to endNight
15%6%344245%45%43%
2558
December1st to 15thNight
18%8%25%433445%38%
2532
16th to endNight
17%9%35%3345%5%7%35%
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
45%6%10%23%10%2
1433
16th to endDay
39%6%15%24%12%1
1536
February1st to 15thDay
50%7%13%17%10%
1647
16th to endDay
47%5%11%18%13%3
1580
March1st to 15thDay
49%6%11%17%13%2
1800
16th to endDay
44%5%9%19%15%5%
2202
April1st to 15thDay
48%5%9%19%14%2
2152
16th to endDay
44%5%9%19%16%3
2276
May1st to 15thDay
54%5%7%18%12%2
2342
16th to endDay
46%8%12%18%12%1
2622
June1st to 15thDay
51%6%13%17%9%
2520
16th to endDay
47%8%14%17%11%
2520
July1st to 15thDay
44%8%12%19%13%1
2371
16th to endDay
43%7%14%21%11%1
2487
August1st to 15thDay
44%7%14%21%10%1
2380
16th to endDay
36%7%13%25%14%2
2315
September1st to 15thDay
39%6%11%21%18%1
2115
16th to endDay
35%48%24%24%2
1980
October1st to 15thDay
46%5%9%24%12%2
1929
16th to endDay
44%6%12%22%12%2
1734
November1st to 15thDay
43%5%13%22%13%1
1716
16th to endDay
42%413%21%14%2
1729
December1st to 15thDay
46%6%14%18%13%
1442
16th to endDay
51%6%13%18%9%
1536
January1st to 15thNight
43%8%12%21%12%2
2506
16th to endNight
44%5%12%20%14%2
2688
February1st to 15thNight
45%7%15%19%11%1
2214
16th to endNight
44%5%12%22%11%3
1893
March1st to 15thNight
46%6%11%20%12%2
2160
16th to endNight
39%6%11%17%18%5%
2017
April1st to 15thNight
45%5%11%17%17%1
1796
16th to endNight
45%5%10%18%16%3
1683
May1st to 15thNight
48%6%10%17%14%2
1620
16th to endNight
48%8%13%18%10%1
1497
June1st to 15thNight
49%5%13%20%9%
1440
16th to endNight
41%9%13%20%14%
1440
July1st to 15thNight
37%9%14%25%12%
1360
16th to endNight
36%7%17%25%11%1
1418
August1st to 15thNight
36%9%15%22%14%1
1542
16th to endNight
35%8%11%28%16%
1884
September1st to 15thNight
34%6%13%25%19%
1844
16th to endNight
33%5%9%26%24%1
1980
October1st to 15thNight
41%5%11%23%14%3
2031
16th to endNight
44%6%13%23%11%
2489
November1st to 15thNight
42%5%12%20%16%2
2472
16th to endNight
41%5%14%23%12%2
2558
December1st to 15thNight
47%5%15%20%10%
2532
16th to endNight
46%6%13%21%10%
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%23%33%15%3
60
16th to endDay
31%21%31%14%1
64
February1st to 15thDay
28%23%34%11%1
189
16th to endDay
20%27%31%17%2
239
March1st to 15thDay
30%24%29%12%3
270
16th to endDay
25%26%29%9%6%2
288
April1st to 15thDay
25%22%33%11%6%1
270
16th to endDay
23%17%31%17%7%2
270
May1st to 15thDay
33%18%25%13%7%2
288
16th to endDay
19%15%36%22%5%
331
June1st to 15thDay
25%13%33%19%6%1
315
16th to endDay
15%14%38%22%7%1
315
July1st to 15thDay
18%7%33%28%10%1
305
16th to endDay
13%8%32%30%12%3
326
August1st to 15thDay
13%10%31%25%15%3
313
16th to endDay
14%9%24%29%17%5%
332
September1st to 15thDay
17%10%30%19%15%5%
315
16th to endDay
17%11%24%18%14%13%
314
October1st to 15thDay
23%11%26%21%12%4
315
16th to endDay
25%17%29%20%6%
289
November1st to 15thDay
21%18%28%20%9%1
280
16th to endDay
25%22%24%19%5%1
259
December1st to 15thDay
25%31%28%11%3
60
16th to endDay
37%28%28%33
64
January1st to 15thNight
23%24%36%14%1
720
16th to endNight
23%23%36%14%1
768
February1st to 15thNight
21%24%39%13%1
704
16th to endNight
24%25%32%15%1
631
March1st to 15thNight
27%21%32%16%2
720
16th to endNight
22%21%32%17%5%
768
April1st to 15thNight
23%19%36%17%3
718
16th to endNight
24%19%30%18%6%
603
May1st to 15thNight
24%15%34%20%5%
540
16th to endNight
21%8%37%26%5%
375
June1st to 15thNight
25%9%34%22%8%
360
16th to endNight
16%6%37%33%5%
360
July1st to 15thNight
13%5%31%38%8%1
340
16th to endNight
13%332%36%13%
376
August1st to 15thNight
13%6%31%36%11%
471
16th to endNight
15%427%33%16%2
738
September1st to 15thNight
17%7%33%28%11%1
720
16th to endNight
15%8%28%26%18%3
717
October1st to 15thNight
22%11%28%24%10%1
720
16th to endNight
24%20%29%20%5%
768
November1st to 15thNight
20%19%28%21%7%1
760
16th to endNight
23%19%31%18%6%1
780
December1st to 15thNight
23%24%32%15%3
724
16th to endNight
26%23%35%12%2
768
Page generated at 2017-12-02 09:14:19. Version ac04

Copyright 2017 A. Danko


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