Nightly cloud cover statistics, as measured in Trenton, Ontario, are presented here. These plots have been derived from detailed data obtained from Environment Canada. Comparable statistics for Kingston itself are not available, since the Kingston airport does not make hourly measurements of cloud cover throughout the night^1. The plots are of percentage of the sky that is covered by clouds during nighttime hours. Here, "Nighttime hours" are taken to be 7 pm to 6 am. Also, according to Environment Canada, "covered" does not necessarily mean "concealed" (the latter implying optical thickness). Therefore, visual or other non-scientific observations of astronomical objects may be somewhat more successful than the following data would suggest.
| Year | # Hrs with Clear Skies | Total # Nighttime Hrs | % Clear |
|---|---|---|---|
| 1996 | 1004 | 4019 | 24.98 |
| 1997 | 973 | 4002 | 24.31 |
| 1998 | 1004 | 4013 | 25.02 |
| 1999 | 1240 | 3988 | 31.09 |
| 2000 | 1043 | 4013 | 25.99 |
LEFT PLOT: Average Cloud Cover for the hours, 7 pm to midnight, for each
day of the year.
CENTER PLOT: Average Cloud Cover for the hours, 1 am to 6am, for each
day of the year.
RIGHT PLOT: Average Cloud Cover for all night hours, 7 pm to 6 am, for each
day of the year.
1996:
1997:
1998:
1999:
2000:
The following plots show nightly cloud cover averaged over each month.
Each plot shows both 7 pm to midnight bars (light purple) and
1 am to 6 am bars (dark purple)
1996:
1997:
1998:
1999:
2000:
The final plot shows nightly (7 pm to 6 am) cloud cover averaged for each month
and averaged over all 5 years.
