Brandon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brandon clear sky chart from 2005-11-05 to 2018-01-20.

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
38%
16869
13%
48513
7%
16828
43%
16828
21%
33992

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
28%
973
11%
2878
7%
970
32%
970
15%
2178
January16th to endNight
24%
985
11%
2758
3%
985
31%
985
14%
2151
February1st to 15thNight
33%
875
10%
2420
3%
875
39%
875
19%
1799
February16th to endNight
41%
673
15%
1935
9%
673
46%
673
21%
1392
March1st to 15thNight
35%
695
11%
2135
7%
695
40%
695
17%
1563
March16th to endNight
40%
576
13%
2067
11%
576
46%
576
16%
1440
April1st to 15thNight
41%
539
15%
1737
12%
539
50%
539
23%
1113
April16th to endNight
38%
540
13%
1620
10%
540
42%
540
20%
1145
May1st to 15thNight
40%
540
11%
1482
4%
540
42%
540
23%
1036
May16th to endNight
42%
563
11%
1311
5%
561
44%
561
28%
949
June1st to 15thNight
40%
540
4%
1260
2%
540
43%
540
32%
871
June16th to endNight
50%
540
4%
1260
3%
540
52%
540
33%
856
July1st to 15thNight
57%
510
6%
1190
3%
510
59%
510
43%
740
July16th to endNight
64%
564
13%
1347
7%
531
65%
531
46%
784
August1st to 15thNight
60%
539
17%
1470
9%
536
63%
536
39%
868
August16th to endNight
59%
573
23%
1719
20%
573
64%
573
38%
967
September1st to 15thNight
55%
540
17%
1839
15%
540
61%
540
33%
1019
September16th to endNight
44%
537
21%
1980
19%
537
52%
537
25%
1160
October1st to 15thNight
37%
667
16%
2107
10%
667
43%
667
21%
1390
October16th to endNight
35%
960
16%
2496
7%
960
39%
960
22%
1785
November1st to 15thNight
32%
950
14%
2555
5%
950
37%
950
21%
1846
November16th to endNight
29%
975
13%
2902
6%
975
36%
975
16%
2124
December1st to 15thNight
27%
975
6%
2925
3%
975
30%
975
11%
2366
December16th to endNight
25%
1040
10%
3120
5%
1040
31%
1040
12%
2450

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%8%46%6%35%45%7%34%
49034
Night
11%9%47%6%345%5%7%35%
48668
Cloud CoverDay
12%8%46%6%35%45%7%34%
49043
Night
10%9%47%6%35%45%7%35%
48672
Cloud CoverDay
12%8%46%5%35%45%7%34%
49044
Night
11%9%47%6%345%5%7%35%
48673
Cloud CoverDay
12%8%37%5%35%45%7%35%
49042
Night
11%9%47%6%3445%7%35%
48673
TransparencyDay
47%7%14%22%7%
48706
Night
47%6%14%22%8%
48513
SeeingDay
16%6%28%28%16%3
6644
Night
15%5%29%32%14%1
16876

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
7%13%6%9%7%46%5%6%8%25%
1387
16th to endDay
7%14%6%9%9%46%45%8%23%
1570
February1st to 15thDay
9%11%5%9%9%36%45%7%26%
1443
16th to endDay
10%13%5%8%8%47%7%6%6%21%
1548
March1st to 15thDay
9%13%6%9%8%46%46%7%23%
1814
16th to endDay
13%10%6%9%7%35%5%5%6%25%
2156
April1st to 15thDay
11%9%46%425%45%7%36%
2210
16th to endDay
16%9%35%7%35%445%34%
2340
May1st to 15thDay
19%9%36%5%23346%34%
2468
16th to endDay
21%7%345%25%45%8%32%
2803
June1st to 15thDay
16%6%36%6%45%5%6%7%30%
2700
16th to endDay
14%6%26%5%35%46%7%36%
2700
July1st to 15thDay
8%425%5%35%5%6%9%42%
2700
16th to endDay
7%424435%6%7%10%44%
2724
August1st to 15thDay
9%5%25%5%345%5%8%43%
2481
16th to endDay
9%41343445%7%51%
2483
September1st to 15thDay
9%6%25%4235%5%6%47%
2121
16th to endDay
14%5%235%24445%46%
1980
October1st to 15thDay
15%10%37%433336%39%
1837
16th to endDay
14%11%46%6%3335%5%35%
1728
November1st to 15thDay
15%11%6%7%5%3435%6%31%
1633
16th to endDay
11%14%5%9%6%25%447%27%
1387
December1st to 15thDay
10%13%8%12%10%446%5%6%15%
1365
16th to endDay
10%14%7%10%7%46%45%7%20%
1456
January1st to 15thNight
9%12%5%9%7%46%6%47%26%
2878
16th to endNight
9%13%6%10%6%36%6%5%6%24%
2758
February1st to 15thNight
9%10%49%8%45%5%6%7%29%
2417
16th to endNight
9%10%5%7%7%35%5%6%8%29%
1935
March1st to 15thNight
10%12%48%6%35%5%6%7%28%
2122
16th to endNight
12%9%36%6%45%5%5%8%31%
2067
April1st to 15thNight
7%8%37%6%26%5%5%6%40%
1737
16th to endNight
16%9%35%6%3445%7%32%
1620
May1st to 15thNight
17%7%26%43445%7%36%
1482
16th to endNight
19%7%2441436%7%38%
1310
June1st to 15thNight
15%425%5%2446%8%40%
1260
16th to endNight
9%425%4245%5%11%43%
1260
July1st to 15thNight
8%31342436%7%54%
1260
16th to endNight
321342446%10%56%
1441
August1st to 15thNight
7%31342445%8%53%
1478
16th to endNight
8%41441335%7%55%
1719
September1st to 15thNight
8%5%2342345%6%53%
1839
16th to endNight
14%5%24413347%46%
1980
October1st to 15thNight
13%7%35%6%34447%39%
2107
16th to endNight
14%9%35%6%34446%36%
2496
November1st to 15thNight
12%11%47%6%2445%7%34%
2555
16th to endNight
11%10%48%7%2445%7%31%
2902
December1st to 15thNight
9%14%6%11%9%46%5%5%7%18%
2925
16th to endNight
9%14%8%11%7%35%5%6%7%20%
3120

Percentage Cloud Cover NW (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
6%13%6%10%7%46%5%7%7%25%
1388
16th to endDay
7%14%6%8%9%45%45%8%23%
1570
February1st to 15thDay
9%10%5%10%9%36%5%6%6%26%
1443
16th to endDay
11%12%5%8%8%5%7%7%6%6%21%
1548
March1st to 15thDay
9%14%6%9%8%36%46%7%23%
1824
16th to endDay
13%10%5%9%7%35%45%7%25%
2154
April1st to 15thDay
11%8%46%5%345%6%7%36%
2210
16th to endDay
16%9%36%6%34445%33%
2340
May1st to 15thDay
19%8%36%5%34346%34%
2468
16th to endDay
20%7%25%43445%8%31%
2803
June1st to 15thDay
16%6%36%6%46%5%6%7%30%
2700
16th to endDay
14%5%26%5%45%5%5%7%36%
2700
July1st to 15thDay
8%4245%35%5%6%9%42%
2700
16th to endDay
7%3245%25%6%7%10%44%
2724
August1st to 15thDay
9%425%5%35%5%5%8%43%
2481
16th to endDay
8%42342445%8%51%
2483
September1st to 15thDay
9%6%25%5%235%5%6%46%
2121
16th to endDay
15%5%245%24345%46%
1980
October1st to 15thDay
15%10%36%433326%39%
1837
16th to endDay
14%10%46%6%3435%6%34%
1728
November1st to 15thDay
15%10%7%7%5%35%445%31%
1633
16th to endDay
10%15%5%8%6%25%447%27%
1387
December1st to 15thDay
11%13%8%13%10%45%6%6%6%15%
1365
16th to endDay
10%14%7%9%8%36%5%6%7%19%
1456
January1st to 15thNight
9%12%5%10%6%46%5%47%25%
2878
16th to endNight
9%13%6%10%6%37%6%5%7%24%
2758
February1st to 15thNight
9%10%5%9%7%45%5%6%7%29%
2410
16th to endNight
9%9%6%8%6%46%5%5%8%30%
1935
March1st to 15thNight
11%12%49%6%35%46%7%28%
2135
16th to endNight
12%9%46%6%446%5%8%31%
2065
April1st to 15thNight
7%8%36%5%35%5%5%7%40%
1737
16th to endNight
17%9%35%6%34447%32%
1620
May1st to 15thNight
16%8%26%434447%36%
1481
16th to endNight
19%7%3432436%7%37%
1311
June1st to 15thNight
15%5%2442446%8%40%
1260
16th to endNight
9%425%3245%5%10%44%
1260
July1st to 15thNight
8%32242337%7%53%
1260
16th to endNight
321343347%9%56%
1441
August1st to 15thNight
7%31442445%9%52%
1478
16th to endNight
8%31432325%8%55%
1719
September1st to 15thNight
8%5%2342345%6%53%
1839
16th to endNight
14%6%25%323447%46%
1980
October1st to 15thNight
13%7%35%6%3445%7%39%
2107
16th to endNight
14%8%35%6%35%446%36%
2496
November1st to 15thNight
12%11%47%5%24448%33%
2555
16th to endNight
11%10%49%7%2445%7%31%
2902
December1st to 15thNight
9%14%6%12%9%46%5%6%6%18%
2925
16th to endNight
9%14%7%11%7%35%5%6%7%19%
3120

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
7%12%6%9%7%35%6%6%8%25%
1387
16th to endDay
8%13%6%8%8%46%35%8%24%
1570
February1st to 15thDay
9%11%410%9%36%5%5%7%26%
1443
16th to endDay
10%14%49%7%47%6%5%7%21%
1548
March1st to 15thDay
9%13%6%9%8%5%5%46%8%22%
1824
16th to endDay
14%10%5%9%7%345%6%6%26%
2156
April1st to 15thDay
10%10%46%435%46%7%36%
2210
16th to endDay
17%9%36%6%34346%34%
2340
May1st to 15thDay
19%9%36%5%33345%34%
2468
16th to endDay
20%7%3443445%7%32%
2803
June1st to 15thDay
16%6%36%5%46%5%6%7%30%
2700
16th to endDay
14%6%25%5%35%5%6%8%36%
2700
July1st to 15thDay
8%425%5%35%5%6%9%42%
2700
16th to endDay
7%424435%5%6%10%45%
2724
August1st to 15thDay
10%5%25%5%35%45%8%43%
2481
16th to endDay
9%413334447%52%
2483
September1st to 15thDay
10%6%26%424446%47%
2121
16th to endDay
15%5%145%24345%46%
1980
October1st to 15thDay
15%9%37%5%23236%39%
1837
16th to endDay
14%10%46%5%3435%6%35%
1728
November1st to 15thDay
15%11%7%7%5%2345%6%30%
1633
16th to endDay
12%13%5%10%5%25%45%6%28%
1387
December1st to 15thDay
10%12%7%13%10%45%5%6%7%15%
1365
16th to endDay
10%14%7%11%6%47%45%7%20%
1456
January1st to 15thNight
9%12%5%9%8%45%6%5%7%26%
2878
16th to endNight
9%13%6%9%6%36%6%5%7%24%
2758
February1st to 15thNight
9%10%49%8%45%5%5%7%29%
2410
16th to endNight
9%10%6%7%6%35%5%6%8%29%
1935
March1st to 15thNight
11%12%5%7%6%35%45%7%28%
2135
16th to endNight
12%9%37%6%346%5%8%31%
2067
April1st to 15thNight
7%8%37%5%35%5%5%6%41%
1737
16th to endNight
17%10%35%6%3446%6%33%
1620
May1st to 15thNight
17%7%36%425%45%6%36%
1481
16th to endNight
19%6%3432437%6%38%
1310
June1st to 15thNight
16%425%42446%8%41%
1260
16th to endNight
9%425%425%5%6%10%44%
1260
July1st to 15thNight
9%31332345%8%53%
1260
16th to endNight
3234245%6%9%56%
1441
August1st to 15thNight
7%4133245%5%8%52%
1478
16th to endNight
9%313423447%55%
1719
September1st to 15thNight
8%42432345%6%53%
1839
16th to endNight
14%5%24423447%46%
1980
October1st to 15thNight
13%7%25%6%34447%40%
2107
16th to endNight
14%9%35%5%34447%36%
2496
November1st to 15thNight
12%11%5%6%6%2345%7%34%
2555
16th to endNight
11%10%48%7%245%5%7%32%
2902
December1st to 15thNight
9%14%6%11%10%46%45%7%18%
2925
16th to endNight
10%14%7%12%7%45%5%5%7%20%
3120

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
7%12%5%9%6%45%5%5%10%26%
1387
16th to endDay
8%13%5%9%7%47%447%25%
1570
February1st to 15thDay
9%11%39%8%46%5%6%7%27%
1443
16th to endDay
11%13%48%9%47%5%5%7%23%
1548
March1st to 15thDay
10%12%5%10%7%46%45%8%23%
1824
16th to endDay
14%10%5%9%7%4445%7%25%
2154
April1st to 15thDay
10%9%46%5%2446%7%37%
2210
16th to endDay
16%8%27%5%35%446%35%
2340
May1st to 15thDay
19%9%36%5%24335%34%
2468
16th to endDay
20%7%25%43445%8%31%
2803
June1st to 15thDay
17%6%36%5%45%5%6%6%31%
2700
16th to endDay
14%6%35%445%5%6%8%36%
2700
July1st to 15thDay
9%4245%36%6%6%9%42%
2700
16th to endDay
7%4144346%7%9%45%
2724
August1st to 15thDay
10%5%25%6%35%45%8%43%
2481
16th to endDay
9%4243235%5%7%51%
2483
September1st to 15thDay
10%5%26%42445%6%47%
2121
16th to endDay
15%425%423445%46%
1980
October1st to 15thDay
15%9%37%423335%40%
1837
16th to endDay
14%10%46%6%2435%6%34%
1728
November1st to 15thDay
15%11%6%7%6%24346%31%
1633
16th to endDay
12%12%5%9%5%35%45%6%29%
1387
December1st to 15thDay
10%12%7%13%9%45%6%5%7%17%
1365
16th to endDay
10%13%7%11%6%45%5%5%7%21%
1456
January1st to 15thNight
10%11%6%8%8%36%5%47%27%
2878
16th to endNight
10%12%7%9%6%45%5%5%7%25%
2758
February1st to 15thNight
9%9%48%8%5%5%5%5%7%30%
2410
16th to endNight
9%10%5%7%6%45%6%6%8%31%
1935
March1st to 15thNight
12%12%6%7%6%35%45%7%28%
2135
16th to endNight
13%9%46%5%445%5%8%32%
2067
April1st to 15thNight
7%7%36%5%36%5%6%5%41%
1737
16th to endNight
16%9%36%445%45%6%33%
1620
May1st to 15thNight
17%8%25%5%245%5%7%36%
1481
16th to endNight
19%6%2432436%7%38%
1310
June1st to 15thNight
15%43433445%8%41%
1260
16th to endNight
10%425%3345%6%10%43%
1260
July1st to 15thNight
8%31432345%8%53%
1260
16th to endNight
33134145%5%9%57%
1441
August1st to 15thNight
8%41342446%7%52%
1478
16th to endNight
8%313423447%55%
1719
September1st to 15thNight
8%42443345%6%53%
1839
16th to endNight
14%5%24423446%46%
1980
October1st to 15thNight
13%7%25%5%3345%8%39%
2107
16th to endNight
14%8%35%5%345%47%37%
2496
November1st to 15thNight
11%11%5%6%5%3445%6%34%
2555
16th to endNight
11%11%48%6%35%45%6%32%
2902
December1st to 15thNight
9%13%7%11%9%46%5%5%7%19%
2925
16th to endNight
10%14%7%11%8%45%5%47%20%
3120

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
54%7%11%20%6%
1388
16th to endDay
57%7%10%18%5%
1570
February1st to 15thDay
54%6%17%17%4
1444
16th to endDay
59%6%11%16%5%
1548
March1st to 15thDay
59%6%12%17%4
1824
16th to endDay
57%7%13%16%4
2156
April1st to 15thDay
45%6%16%22%8%1
2210
16th to endDay
51%6%11%16%11%
2340
May1st to 15thDay
51%411%23%7%1
2468
16th to endDay
50%5%12%20%9%
2807
June1st to 15thDay
49%8%14%18%8%
2700
16th to endDay
44%8%17%22%5%
2700
July1st to 15thDay
35%9%19%27%7%
2541
16th to endDay
32%9%19%28%9%
2555
August1st to 15thDay
37%8%20%25%7%
2465
16th to endDay
30%6%17%34%10%
2483
September1st to 15thDay
36%6%18%29%7%1
2121
16th to endDay
39%6%13%30%9%
1980
October1st to 15thDay
48%411%26%8%
1837
16th to endDay
50%6%14%21%7%
1728
November1st to 15thDay
54%5%13%17%7%1
1633
16th to endDay
55%5%17%16%4
1387
December1st to 15thDay
66%9%10%11%2
1365
16th to endDay
60%7%11%14%5%
1456
January1st to 15thNight
55%7%10%18%7%
2878
16th to endNight
56%8%13%13%7%
2758
February1st to 15thNight
52%6%15%18%7%
2420
16th to endNight
50%5%13%20%9%
1935
March1st to 15thNight
53%6%15%18%5%
2135
16th to endNight
49%7%15%21%4
2067
April1st to 15thNight
41%6%11%23%14%1
1737
16th to endNight
51%412%17%12%1
1620
May1st to 15thNight
46%5%11%23%11%
1482
16th to endNight
45%6%10%21%15%
1311
June1st to 15thNight
39%6%17%25%9%
1260
16th to endNight
34%9%21%25%7%
1260
July1st to 15thNight
28%6%17%34%12%
1190
16th to endNight
22%7%18%36%12%1
1347
August1st to 15thNight
28%7%17%35%10%1
1470
16th to endNight
28%6%14%33%15%2
1719
September1st to 15thNight
30%6%16%30%15%1
1839
16th to endNight
37%5%15%28%12%
1980
October1st to 15thNight
43%6%14%25%8%
2107
16th to endNight
47%6%14%24%7%
2496
November1st to 15thNight
49%6%15%20%7%1
2555
16th to endNight
51%8%15%19%5%
2902
December1st to 15thNight
64%7%12%13%3
2925
16th to endNight
61%6%12%13%6%
3120

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
11%5%33%32%17%
135
16th to endDay
17%7%29%27%18%
109
February1st to 15thDay
17%348%20%10%
90
16th to endDay
13%335%30%14%1
81
March1st to 15thDay
13%14%21%42%8%
90
16th to endDay
25%5%34%17%16%2
140
April1st to 15thDay
15%10%32%27%11%1
329
16th to endDay
18%6%31%27%12%2
450
May1st to 15thDay
22%6%28%29%11%1
468
16th to endDay
21%7%26%24%17%2
517
June1st to 15thDay
17%9%27%26%13%4
495
16th to endDay
16%8%25%30%15%3
495
July1st to 15thDay
10%323%33%21%7%
475
16th to endDay
8%7%25%30%22%5%
515
August1st to 15thDay
11%326%30%17%9%
493
16th to endDay
10%6%22%30%24%5%
523
September1st to 15thDay
12%7%35%25%16%2
276
16th to endDay
23%6%26%28%11%2
135
October1st to 15thDay
20%8%34%25%8%1
135
16th to endDay
28%9%30%18%10%2
144
November1st to 15thDay
17%8%31%24%17%2
135
16th to endDay
25%7%30%26%8%1
135
December1st to 15thDay
17%8%37%20%13%3
135
16th to endDay
11%240%32%9%3
144
January1st to 15thNight
16%6%33%31%11%1
975
16th to endNight
16%8%37%29%7%
985
February1st to 15thNight
14%5%32%31%12%3
880
16th to endNight
12%329%35%15%3
673
March1st to 15thNight
16%6%28%30%13%3
695
16th to endNight
17%425%33%16%2
576
April1st to 15thNight
10%5%33%35%13%1
539
16th to endNight
20%428%33%12%1
540
May1st to 15thNight
21%7%27%30%12%
540
16th to endNight
20%5%26%33%14%
563
June1st to 15thNight
17%432%29%16%
540
16th to endNight
12%328%37%18%
540
July1st to 15thNight
10%322%36%25%
510
16th to endNight
5%123%47%20%1
564
August1st to 15thNight
9%122%40%22%3
539
16th to endNight
10%322%37%22%2
573
September1st to 15thNight
11%325%37%19%2
540
16th to endNight
15%7%25%33%16%1
537
October1st to 15thNight
17%7%32%30%11%
667
16th to endNight
19%7%30%31%10%
960
November1st to 15thNight
16%8%32%29%11%2
950
16th to endNight
17%8%35%28%8%1
975
December1st to 15thNight
15%6%32%29%12%3
975
16th to endNight
17%7%29%29%12%3
1040
Page generated at 2018-01-21 11:19:21. Version ac04

Copyright 2018 A. Danko


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