Observatorio Las Palmas
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatorio Las Palmas clear sky chart from 2005-11-06 to 2024-07-31.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Transparency	Day	16% 3 6% 10% 23% 42%	89855
	Night	18% 3 6% 10% 24% 40%	89689
Seeing	Day	4 4 18% 35% 28% 12%	14677
	Night	4 1 13% 42% 33% 6%	24822

By Month

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 1 3 9% 30% 47%	2859
	11th to 20th	Day	15% 2 4 8% 26% 45%	2860
	21st to end	Day	24% 2 5% 11% 28% 30%	3146
February	1st to 10th	Day	18% 2 5% 7% 22% 46%	1858
	11th to 20th	Day	21% 2 5% 7% 25% 40%	1860
	21st to end	Day	18% 1 5% 8% 26% 42%	1721
March	1st to 10th	Day	22% 1 4 6% 25% 42%	3444
	11th to 20th	Day	18% 1 5% 9% 28% 39%	3490
	21st to end	Day	23% 1 6% 4 25% 41%	3825
April	1st to 10th	Day	14% 1 2 5% 20% 57%	2090
	11th to 20th	Day	11% 1 2 4 20% 63%	2163
	21st to end	Day	7% 1 2 5% 19% 66%	2280
May	1st to 10th	Day	5% 1 1 2 15% 76%	3913
	11th to 20th	Day	4 1 2 3 16% 74%	4074
	21st to end	Day	4 1 2 13% 80%	4477
June	1st to 10th	Day	10% 1 4 4 24% 58%	2470
	11th to 20th	Day	7% 1 3 4 25% 60%	2470
	21st to end	Day	16% 4 7% 12% 26% 36%	2470
July	1st to 10th	Day	26% 9% 14% 16% 18% 16%	2406
	11th to 20th	Day	28% 12% 21% 23% 12% 3	2401
	21st to end	Day	33% 12% 19% 26% 9% 2	2536
August	1st to 10th	Day	24% 10% 17% 24% 19% 7%	2313
	11th to 20th	Day	30% 11% 16% 23% 15% 6%	2228
	21st to end	Day	26% 9% 16% 24% 17% 8%	2237
September	1st to 10th	Day	30% 6% 13% 21% 20% 10%	1980
	11th to 20th	Day	15% 4 6% 16% 32% 28%	1980
	21st to end	Day	15% 3 6% 13% 31% 32%	1980
October	1st to 10th	Day	11% 2 5% 14% 31% 36%	1926
	11th to 20th	Day	14% 2 4 9% 26% 45%	1800
	21st to end	Day	10% 1 3 9% 24% 53%	1980
November	1st to 10th	Day	11% 1 3 10% 23% 52%	1859
	11th to 20th	Day	15% 1 3 8% 26% 47%	1900
	21st to end	Day	20% 2 5% 12% 25% 36%	1835
December	1st to 10th	Day	20% 2 5% 12% 23% 38%	1710
	11th to 20th	Day	25% 2 5% 11% 26% 32%	2168
	21st to end	Day	13% 2 5% 8% 42% 31%	3146
January	1st to 10th	Night	11% 1 4 9% 29% 45%	4097
	11th to 20th	Night	13% 2 3 7% 29% 47%	4110
	21st to end	Night	25% 2 6% 11% 29% 26%	4521
February	1st to 10th	Night	19% 2 4 7% 24% 44%	2318
	11th to 20th	Night	22% 2 5% 11% 24% 37%	2219
	21st to end	Night	22% 2 3 7% 25% 42%	1731
March	1st to 10th	Night	22% 1 4 6% 29% 38%	3430
	11th to 20th	Night	15% 2 4 13% 26% 40%	3490
	21st to end	Night	22% 1 4 7% 26% 39%	3828
April	1st to 10th	Night	13% 1 2 6% 25% 53%	2090
	11th to 20th	Night	13% 1 1 5% 23% 57%	1967
	21st to end	Night	8% 1 2 6% 18% 66%	1900
May	1st to 10th	Night	5% 1 1 2 15% 76%	3052
	11th to 20th	Night	5% 3 3 17% 72%	2835
	21st to end	Night	4 2 1 16% 77%	3110
June	1st to 10th	Night	9% 1 2 5% 23% 59%	1710
	11th to 20th	Night	9% 1 4 5% 22% 59%	1710
	21st to end	Night	21% 4 8% 10% 23% 34%	1710
July	1st to 10th	Night	31% 9% 13% 15% 18% 14%	1665
	11th to 20th	Night	37% 13% 19% 22% 7% 2	1656
	21st to end	Night	43% 15% 18% 18% 4 2	1773
August	1st to 10th	Night	31% 10% 18% 20% 16% 5%	1602
	11th to 20th	Night	29% 14% 20% 20% 13% 4	1671
	21st to end	Night	26% 11% 19% 23% 13% 8%	2113
September	1st to 10th	Night	30% 10% 15% 21% 18% 6%	1980
	11th to 20th	Night	14% 3 7% 20% 29% 27%	1980
	21st to end	Night	13% 3 7% 19% 27% 31%	1980
October	1st to 10th	Night	9% 2 5% 14% 31% 39%	2032
	11th to 20th	Night	15% 2 3 12% 24% 44%	2160
	21st to end	Night	9% 1 3 9% 27% 51%	2376
November	1st to 10th	Night	11% 1 3 10% 23% 51%	2220
	11th to 20th	Night	17% 2 3 7% 27% 44%	2280
	21st to end	Night	23% 2 4 12% 25% 35%	2341
December	1st to 10th	Night	19% 2 5% 14% 26% 34%	2470
	11th to 20th	Night	23% 2 5% 10% 29% 32%	3041
	21st to end	Night	18% 2 5% 8% 32% 34%	4521

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	4 4 22% 42% 26% 2	270
	11th to 20th	Day	6% 3 15% 39% 31% 6%	270
	21st to end	Day	4 7% 24% 38% 24% 4	297
February	1st to 10th	Day	6% 7% 22% 37% 24% 5%	418
	11th to 20th	Day	10% 9% 27% 37% 15% 2	455
	21st to end	Day	7% 9% 35% 35% 12% 3	382
March	1st to 10th	Day	8% 8% 29% 35% 15% 3	460
	11th to 20th	Day	7% 7% 29% 31% 19% 7%	460
	21st to end	Day	5% 10% 33% 35% 12% 4	506
April	1st to 10th	Day	4 8% 32% 32% 19% 6%	460
	11th to 20th	Day	3 8% 33% 38% 12% 6%	452
	21st to end	Day	1 9% 31% 32% 20% 7%	460
May	1st to 10th	Day	1 9% 32% 34% 18% 6%	463
	11th to 20th	Day	1 5% 30% 41% 22% 2	488
	21st to end	Day	5% 24% 46% 22% 3	529
June	1st to 10th	Day	2 2 18% 48% 26% 4	490
	11th to 20th	Day	1 1 16% 47% 26% 9%	490
	21st to end	Day	2 12% 39% 35% 11%	490
July	1st to 10th	Day	3 8% 35% 33% 20%	486
	11th to 20th	Day	4 4 30% 38% 23%	484
	21st to end	Day	7% 1 7% 27% 35% 22%	528
August	1st to 10th	Day	3 1 5% 23% 39% 29%	447
	11th to 20th	Day	6% 2 3 22% 37% 30%	437
	21st to end	Day	4 1 3 18% 41% 33%	495
September	1st to 10th	Day	7% 1 5% 25% 39% 23%	450
	11th to 20th	Day	4 3 31% 41% 21%	450
	21st to end	Day	4 1 10% 30% 37% 18%	450
October	1st to 10th	Day	3 1 11% 34% 36% 16%	396
	11th to 20th	Day	4 10% 25% 36% 25%	270
	21st to end	Day	2 1 11% 30% 35% 21%	297
November	1st to 10th	Day	4 1 11% 32% 41% 10%	270
	11th to 20th	Day	4 3 11% 32% 38% 12%	270
	21st to end	Day	7% 4 17% 35% 30% 6%	270
December	1st to 10th	Day	7% 3 12% 42% 27% 9%	270
	11th to 20th	Day	3 3 16% 48% 28% 3	270
	21st to end	Day	6% 4 18% 48% 18% 6%	297
January	1st to 10th	Night	3 1 14% 51% 28% 3	760
	11th to 20th	Night	4 1 15% 50% 28% 2	760
	21st to end	Night	8% 2 21% 44% 22% 3	836
February	1st to 10th	Night	5% 2 18% 47% 25% 3	760
	11th to 20th	Night	7% 1 22% 48% 21% 1	744
	21st to end	Night	5% 1 26% 52% 14% 2	628
March	1st to 10th	Night	8% 3 22% 47% 18% 1	760
	11th to 20th	Night	5% 3 18% 50% 23% 3	760
	21st to end	Night	4 2 21% 48% 24% 2	836
April	1st to 10th	Night	2 1 19% 53% 23% 2	760
	11th to 20th	Night	3 2 22% 51% 21% 1	653
	21st to end	Night	1 1 19% 54% 24% 1	570
May	1st to 10th	Night	1 1 17% 56% 24% 1	570
	11th to 20th	Night	1 14% 52% 32% 1	561
	21st to end	Night	1 1 10% 54% 33% 2	617
June	1st to 10th	Night	2 1 8% 46% 40% 3	570
	11th to 20th	Night	2 1 7% 45% 42% 4	570
	21st to end	Night	2 1 8% 35% 49% 5%	570
July	1st to 10th	Night	4 1 8% 31% 45% 10%	555
	11th to 20th	Night	5% 1 7% 30% 47% 10%	552
	21st to end	Night	7% 3 10% 24% 40% 16%	624
August	1st to 10th	Night	3 1 6% 25% 47% 17%	537
	11th to 20th	Night	4 1 5% 19% 49% 22%	534
	21st to end	Night	6% 1 5% 20% 47% 22%	727
September	1st to 10th	Night	7% 2 4 19% 48% 19%	720
	11th to 20th	Night	4 2 23% 57% 13%	720
	21st to end	Night	3 1 5% 31% 52% 9%	720
October	1st to 10th	Night	2 5% 38% 47% 7%	720
	11th to 20th	Night	4 1 8% 41% 39% 7%	720
	21st to end	Night	1 1 9% 41% 40% 8%	792
November	1st to 10th	Night	1 7% 44% 39% 8%	740
	11th to 20th	Night	4 1 10% 44% 35% 6%	760
	21st to end	Night	7% 2 15% 46% 25% 4	760
December	1st to 10th	Night	6% 2 10% 50% 28% 4	760
	11th to 20th	Night	4 2 13% 55% 23% 3	760
	21st to end	Night	5% 1 18% 49% 24% 4	836

Page generated at 2024-07-28 07:52:11. Version ac07

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