Ice House Observation Plateau
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ice House Observation Plateau clear sky chart from 2005-11-05 to 2017-08-12.

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
60%
15080
27%
46496
22%
15043
66%
15043
37%
25755

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
49%
718
19%
2505
17%
716
55%
716
26%
1467
January16th to endNight
43%
768
23%
2496
16%
768
54%
768
23%
1560
February1st to 15thNight
45%
701
22%
2233
16%
697
54%
697
24%
1417
February16th to endNight
47%
632
23%
1895
19%
632
54%
632
25%
1234
March1st to 15thNight
46%
720
15%
2095
12%
720
51%
720
24%
1421
March16th to endNight
46%
768
18%
2033
12%
768
51%
768
26%
1380
April1st to 15thNight
48%
719
18%
1799
9%
719
52%
719
26%
1270
April16th to endNight
58%
720
22%
1800
11%
720
61%
720
36%
1119
May1st to 15thNight
60%
571
26%
1651
17%
571
65%
571
44%
854
May16th to endNight
69%
374
23%
1496
29%
374
70%
374
33%
734
June1st to 15thNight
72%
360
26%
1440
31%
360
78%
360
40%
649
June16th to endNight
86%
360
35%
1440
46%
360
90%
360
61%
505
July1st to 15thNight
92%
340
33%
1360
43%
340
94%
340
68%
449
July16th to endNight
87%
454
39%
1488
41%
426
89%
426
65%
570
August1st to 15thNight
84%
587
35%
1636
27%
584
85%
584
67%
743
August16th to endNight
87%
700
42%
1750
27%
700
87%
700
78%
797
September1st to 15thNight
88%
660
44%
1650
31%
660
90%
660
81%
744
September16th to endNight
79%
656
41%
1765
34%
656
83%
656
65%
828
October1st to 15thNight
63%
660
30%
1980
27%
660
71%
660
45%
1014
October16th to endNight
65%
704
33%
2116
30%
704
74%
704
45%
1081
November1st to 15thNight
61%
700
28%
2275
26%
700
68%
700
36%
1238
November16th to endNight
51%
720
26%
2385
22%
720
59%
720
31%
1355
December1st to 15thNight
46%
720
21%
2520
16%
720
55%
720
22%
1568
December16th to endNight
38%
768
21%
2688
16%
768
48%
768
18%
1758

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
9%6%12212335%60%
47474
Night
9%6%12213345%58%
46686
TransparencyDay
27%48%18%24%16%
47152
Night
29%48%18%23%15%
46507
SeeingDay
15%16%34%20%8%3
5671
Night
14%6%14%31%27%6%
15087

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
14%8%13223337%48%
1432
16th to endDay
16%12%22322335%44%
1728
February1st to 15thDay
15%8%23313335%47%
1619
16th to endDay
15%16%43312435%38%
1579
March1st to 15thDay
14%14%3342435%6%36%
1863
16th to endDay
15%13%23323447%39%
2190
April1st to 15thDay
13%15%2332335%5%39%
2149
16th to endDay
13%6%24212346%53%
2160
May1st to 15thDay
8%412212347%60%
2295
16th to endDay
12%7%13323335%53%
2615
June1st to 15thDay
7%413222335%61%
2520
16th to endDay
21111123380%
2520
July1st to 15thDay
1111123382%
2520
16th to endDay
1121112382%
2577
August1st to 15thDay
1111222381%
2228
16th to endDay
1111112384%
2100
September1st to 15thDay
11111212382%
1980
16th to endDay
421121223375%
1862
October1st to 15thDay
8%31221335%5%61%
1650
16th to endDay
9%313313335%61%
1755
November1st to 15thDay
8%6%1332445%6%53%
1584
16th to endDay
12%8%23323345%50%
1572
December1st to 15thDay
16%7%24413436%42%
1440
16th to endDay
19%11%33323235%40%
1536
January1st to 15thNight
13%7%24323347%47%
2505
16th to endNight
13%10%23423345%46%
2496
February1st to 15thNight
14%8%2442345%8%42%
2232
16th to endNight
13%12%3321345%5%43%
1895
March1st to 15thNight
16%10%34324446%40%
2095
16th to endNight
14%11%1232345%6%45%
2033
April1st to 15thNight
12%11%24425%346%41%
1799
16th to endNight
10%7%13313346%55%
1800
May1st to 15thNight
7%312213347%62%
1651
16th to endNight
9%5%13223236%60%
1496
June1st to 15thNight
6%41111224467%
1440
16th to endNight
21111212281%
1440
July1st to 15thNight
111223381%
1440
16th to endNight
111111222380%
1590
August1st to 15thNight
111221233376%
1645
16th to endNight
111122483%
1750
September1st to 15thNight
111112286%
1650
16th to endNight
311212225%76%
1765
October1st to 15thNight
6%412212335%64%
1980
16th to endNight
8%211212445%64%
2116
November1st to 15thNight
9%413313347%56%
2275
16th to endNight
10%7%13223346%52%
2385
December1st to 15thNight
16%8%23323436%44%
2520
16th to endNight
21%11%23312235%40%
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
37%5%10%21%19%6%
1432
16th to endDay
42%47%16%17%11%
1728
February1st to 15thDay
39%5%12%16%19%6%
1619
16th to endDay
48%48%23%12%2
1579
March1st to 15thDay
49%5%10%12%16%5%
1863
16th to endDay
45%7%14%17%12%2
2190
April1st to 15thDay
45%5%13%19%14%2
2149
16th to endDay
31%6%13%25%19%4
2160
May1st to 15thDay
23%411%32%22%4
2295
16th to endDay
33%6%11%26%17%4
2619
June1st to 15thDay
24%410%20%24%14%
2520
16th to endDay
10%2317%40%25%
2520
July1st to 15thDay
7%239%29%47%
2371
16th to endDay
9%2411%24%46%
2416
August1st to 15thDay
9%2411%33%39%
2212
16th to endDay
7%1213%42%31%
2100
September1st to 15thDay
9%2411%39%32%
1980
16th to endDay
14%17%24%34%17%
1862
October1st to 15thDay
23%47%23%27%12%
1650
16th to endDay
26%5%8%21%25%12%
1755
November1st to 15thDay
30%5%12%21%19%9%
1584
16th to endDay
35%49%18%26%5%
1572
December1st to 15thDay
44%39%19%17%5%
1440
16th to endDay
47%5%8%14%16%7%
1536
January1st to 15thNight
37%49%19%18%9%
2505
16th to endNight
41%47%13%18%15%
2496
February1st to 15thNight
40%5%8%19%16%8%
2243
16th to endNight
41%5%9%21%17%4
1895
March1st to 15thNight
44%5%9%16%16%6%
2095
16th to endNight
39%8%11%18%16%4
2033
April1st to 15thNight
44%6%12%20%12%4
1799
16th to endNight
30%6%12%26%19%4
1800
May1st to 15thNight
21%5%11%28%25%6%
1652
16th to endNight
26%5%13%28%19%5%
1496
June1st to 15thNight
19%6%9%22%26%15%
1440
16th to endNight
9%3417%35%29%
1440
July1st to 15thNight
7%25%7%28%48%
1360
16th to endNight
11%2410%22%49%
1488
August1st to 15thNight
12%26%11%27%40%
1636
16th to endNight
7%1213%38%35%
1750
September1st to 15thNight
6%25%11%40%33%
1650
16th to endNight
12%26%22%34%20%
1765
October1st to 15thNight
22%47%24%27%13%
1980
16th to endNight
21%48%22%30%13%
2116
November1st to 15thNight
28%5%10%21%22%11%
2275
16th to endNight
32%47%22%24%7%
2385
December1st to 15thNight
41%5%9%17%19%6%
2520
16th to endNight
47%47%11%20%9%
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
50%8%26%6%6%1
60
16th to endDay
32%12%21%21%9%2
256
February1st to 15thDay
25%16%28%20%8%1
244
16th to endDay
31%15%25%21%5%
238
March1st to 15thDay
32%23%16%14%9%3
270
16th to endDay
26%25%25%16%6%
288
April1st to 15thDay
28%23%24%17%6%
269
16th to endDay
20%27%30%15%41
270
May1st to 15thDay
15%23%35%13%9%2
288
16th to endDay
20%16%27%16%11%6%
330
June1st to 15thDay
12%23%33%19%6%4
315
16th to endDay
315%42%24%6%7%
315
July1st to 15thDay
28%52%22%5%8%
305
16th to endDay
110%51%22%8%5%
327
August1st to 15thDay
314%48%21%8%5%
300
16th to endDay
18%55%21%8%3
268
September1st to 15thDay
210%50%23%7%3
255
16th to endDay
6%15%37%31%7%2
255
October1st to 15thDay
11%17%36%25%7%2
255
16th to endDay
16%16%31%26%8%
267
November1st to 15thDay
8%14%11%25%33%6%
90
16th to endDay
21%20%18%26%12%
82
December1st to 15thDay
30%21%23%16%5%3
60
16th to endDay
20%9%23%25%17%4
64
January1st to 15thNight
19%6%20%28%18%6%
720
16th to endNight
21%10%19%25%17%5%
768
February1st to 15thNight
19%8%19%30%17%4
704
16th to endNight
22%9%16%28%18%3
632
March1st to 15thNight
23%7%18%26%19%5%
720
16th to endNight
22%9%19%26%19%3
768
April1st to 15thNight
19%7%19%31%19%2
719
16th to endNight
14%9%13%33%22%6%
720
May1st to 15thNight
10%6%18%33%26%5%
572
16th to endNight
10%410%30%36%6%
375
June1st to 15thNight
7%312%35%35%5%
360
16th to endNight
18%39%43%6%
360
July1st to 15thNight
334%56%5%
340
16th to endNight
15%27%52%12%
454
August1st to 15thNight
27%39%42%8%
587
16th to endNight
17%40%43%6%
700
September1st to 15thNight
17%36%43%10%
660
16th to endNight
4211%35%31%14%
656
October1st to 15thNight
9%6%16%29%27%10%
660
16th to endNight
11%6%13%28%28%11%
704
November1st to 15thNight
12%417%31%25%8%
700
16th to endNight
16%8%20%29%18%6%
720
December1st to 15thNight
23%8%15%31%16%4
720
16th to endNight
29%10%16%25%14%3
768
Page generated at 2017-08-13 11:16:45. Version ac04

Copyright 2017 A. Danko


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