China Lake SV
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the China Lake SV clear sky chart from 2005-11-05 to 2017-04-30.

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
71%
15233
38%
45523
31%
15194
79%
15194
62%
19739

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
71%
716
29%
2506
30%
716
76%
716
49%
1107
January16th to endNight
64%
768
37%
2397
31%
768
74%
768
49%
1143
February1st to 15thNight
66%
697
35%
2103
32%
696
74%
696
52%
1005
February16th to endNight
62%
632
36%
1895
33%
632
72%
632
50%
904
March1st to 15thNight
65%
720
33%
2160
29%
720
76%
720
58%
953
March16th to endNight
59%
768
38%
2022
23%
768
72%
768
62%
956
April1st to 15thNight
57%
719
37%
1799
17%
719
67%
719
58%
900
April16th to endNight
62%
716
40%
1790
18%
716
71%
716
68%
832
May1st to 15thNight
62%
507
42%
1497
27%
507
69%
507
72%
585
May16th to endNight
61%
514
35%
1541
24%
513
68%
513
70%
599
June1st to 15thNight
69%
408
39%
1398
33%
408
78%
408
72%
485
June16th to endNight
80%
330
39%
1320
40%
330
90%
330
85%
370
July1st to 15thNight
87%
310
37%
1240
43%
310
90%
310
65%
420
July16th to endNight
83%
483
35%
1428
30%
450
85%
450
63%
599
August1st to 15thNight
83%
657
40%
1640
25%
653
85%
653
83%
717
August16th to endNight
85%
700
43%
1750
27%
700
86%
700
80%
789
September1st to 15thNight
82%
660
43%
1692
30%
660
87%
660
74%
770
September16th to endNight
85%
656
47%
1815
41%
656
90%
656
85%
712
October1st to 15thNight
77%
660
43%
1815
35%
660
85%
660
67%
815
October16th to endNight
78%
704
45%
2177
42%
704
87%
704
69%
864
November1st to 15thNight
79%
700
38%
2275
39%
700
86%
700
62%
933
November16th to endNight
76%
720
40%
2340
40%
720
82%
720
61%
952
December1st to 15thNight
69%
720
35%
2340
32%
720
77%
720
49%
1070
December16th to endNight
62%
768
34%
2583
31%
768
71%
768
43%
1259

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
111212235%76%
46188
Night
111212235%76%
45717
TransparencyDay
11%35%15%27%36%
45873
Night
11%26%17%29%32%
45533
SeeingDay
410%23%29%23%8%
5252
Night
25%17%39%31%3
15246

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
421221335%9%63%
1432
16th to endDay
5%213323347%61%
1821
February1st to 15thDay
21221335%7%68%
1751
16th to endDay
3212323446%64%
1579
March1st to 15thDay
121111245%8%69%
1800
16th to endDay
111212449%71%
2197
April1st to 15thDay
112212336%74%
2149
16th to endDay
1111235%80%
2150
May1st to 15thDay
1122484%
2122
16th to endDay
11111112481%
2221
June1st to 15thDay
1122484%
2227
16th to endDay
1111188%
2310
July1st to 15thDay
111121323476%
2310
16th to endDay
211112336%74%
2320
August1st to 15thDay
111112385%
1980
16th to endDay
1122385%
2100
September1st to 15thDay
1222384%
1936
16th to endDay
1111388%
1815
October1st to 15thDay
11121323477%
1815
16th to endDay
211111135%78%
1694
November1st to 15thDay
111111246%77%
1584
16th to endDay
12213248%70%
1620
December1st to 15thDay
221342335%9%61%
1620
16th to endDay
3323223349%61%
1635
January1st to 15thNight
2213212346%69%
2506
16th to endNight
422323346%67%
2397
February1st to 15thNight
1213312436%68%
2101
16th to endNight
5%12213347%67%
1895
March1st to 15thNight
111312347%72%
2160
16th to endNight
11111235%8%73%
2022
April1st to 15thNight
112212236%75%
1799
16th to endNight
1111225%81%
1790
May1st to 15thNight
12146%81%
1497
16th to endNight
11113484%
1540
June1st to 15thNight
1113485%
1398
16th to endNight
11390%
1320
July1st to 15thNight
1122233378%
1320
16th to endNight
11213335%75%
1535
August1st to 15thNight
1212385%
1650
16th to endNight
11121385%
1750
September1st to 15thNight
1111212382%
1692
16th to endNight
111389%
1815
October1st to 15thNight
111233478%
1815
16th to endNight
1111113481%
2177
November1st to 15thNight
111212235%77%
2275
16th to endNight
21112336%76%
2340
December1st to 15thNight
3112212237%69%
2340
16th to endNight
4313323247%65%
2583

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
17%310%27%29%11%
1432
16th to endDay
22%49%23%24%14%
1821
February1st to 15thDay
14%48%23%29%18%
1751
16th to endDay
20%5%7%22%29%13%
1579
March1st to 15thDay
12%39%24%29%20%
1800
16th to endDay
11%49%22%30%20%
2197
April1st to 15thDay
14%35%19%33%22%
2149
16th to endDay
8%17%19%32%30%
2150
May1st to 15thDay
6%2416%30%38%
2122
16th to endDay
9%1314%36%33%
2224
June1st to 15thDay
6%1310%23%54%
2227
16th to endDay
6%11413%73%
2310
July1st to 15thDay
10%246%15%60%
2161
16th to endDay
13%3410%20%47%
2165
August1st to 15thDay
6%27%16%66%
1966
16th to endDay
6%225%24%59%
2100
September1st to 15thDay
7%236%19%61%
1936
16th to endDay
4117%30%54%
1815
October1st to 15thDay
11%3312%33%34%
1815
16th to endDay
10%2412%30%38%
1694
November1st to 15thDay
10%27%20%38%20%
1584
16th to endDay
13%38%20%32%21%
1620
December1st to 15thDay
19%5%11%24%28%10%
1620
16th to endDay
23%6%11%26%21%11%
1635
January1st to 15thNight
17%48%24%30%14%
2506
16th to endNight
19%38%21%26%20%
2397
February1st to 15thNight
18%39%20%26%22%
2112
16th to endNight
17%47%24%31%14%
1895
March1st to 15thNight
12%39%21%30%21%
2160
16th to endNight
11%39%27%31%17%
2022
April1st to 15thNight
13%35%23%34%19%
1799
16th to endNight
8%25%23%37%22%
1790
May1st to 15thNight
5%2320%34%32%
1498
16th to endNight
6%26%18%39%27%
1541
June1st to 15thNight
5%2313%25%50%
1398
16th to endNight
327%14%71%
1320
July1st to 15thNight
9%138%14%62%
1240
16th to endNight
12%35%8%23%47%
1428
August1st to 15thNight
5%137%21%60%
1640
16th to endNight
6%125%27%56%
1750
September1st to 15thNight
9%135%24%55%
1692
16th to endNight
4127%28%56%
1815
October1st to 15thNight
9%3312%35%35%
1815
16th to endNight
8%2412%29%42%
2177
November1st to 15thNight
11%2418%36%25%
2275
16th to endNight
11%36%20%28%29%
2340
December1st to 15thNight
17%311%21%31%14%
2340
16th to endNight
21%5%10%25%25%12%
2583

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
16%15%18%31%16%1
60
16th to endDay
11%10%17%26%21%12%
234
February1st to 15thDay
6%10%17%33%22%9%
266
16th to endDay
11%18%17%25%21%5%
238
March1st to 15thDay
6%14%22%23%22%9%
270
16th to endDay
5%14%27%27%19%5%
288
April1st to 15thDay
11%19%22%23%19%3
269
16th to endDay
420%31%28%11%3
267
May1st to 15thDay
215%38%22%16%3
228
16th to endDay
316%28%24%19%8%
266
June1st to 15thDay
311%30%28%20%5%
255
16th to endDay
6%31%25%23%12%
255
July1st to 15thDay
2326%33%23%9%
245
16th to endDay
3218%36%29%8%
271
August1st to 15thDay
5%23%41%18%10%
255
16th to endDay
219%37%25%14%
268
September1st to 15thDay
1323%31%30%7%
255
16th to endDay
25%15%29%34%12%
255
October1st to 15thDay
48%22%34%23%7%
255
16th to endDay
47%16%21%36%13%
201
November1st to 15thDay
2311%20%38%24%
90
16th to endDay
26%16%42%31%1
90
December1st to 15thDay
1312%51%28%3
90
16th to endDay
11%419%37%23%3
81
January1st to 15thNight
3315%41%30%4
720
16th to endNight
5%321%38%27%2
768
February1st to 15thNight
25%19%43%26%3
704
16th to endNight
6%8%20%41%21%2
632
March1st to 15thNight
17%20%43%22%3
720
16th to endNight
29%26%33%25%1
768
April1st to 15thNight
312%24%35%21%1
719
16th to endNight
110%24%36%24%3
716
May1st to 15thNight
7%27%41%20%2
508
16th to endNight
110%25%37%24%
515
June1st to 15thNight
6%23%43%25%
408
16th to endNight
117%48%30%1
330
July1st to 15thNight
1451%38%1
310
16th to endNight
111%43%40%3
483
August1st to 15thNight
13%40%40%4
657
16th to endNight
110%34%46%7%
700
September1st to 15thNight
110%32%48%6%
660
16th to endNight
211%32%47%6%
656
October1st to 15thNight
415%42%33%4
660
16th to endNight
1412%33%41%5%
704
November1st to 15thNight
1312%38%39%4
700
16th to endNight
25%12%37%37%4
720
December1st to 15thNight
46%14%42%28%2
720
16th to endNight
6%5%20%40%24%2
768
Page generated at 2017-04-30 17:40:12. Version ac04

Copyright 2017 A. Danko


China Lake SV Clear Sky Chart | Charts Home