90W 45N Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the 90W 45N Park clear sky chart from 2005-11-05 to 2024-10-14.

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
Cloud Cover	Day	14% 9% 3 8% 5% 4 5% 4 5% 7% 36%	101380
	Night	13% 10% 4 8% 5% 4 4 4 5% 6% 37%	97261
Transparency	Day	47% 5% 12% 24% 11% 1	101173
	Night	47% 5% 12% 23% 12% 1	97144
Seeing	Day	16% 10% 29% 26% 14% 5%	15956
	Night	17% 9% 31% 30% 11% 1	25787

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 17% 7% 15% 6% 4 4 3 4 7% 23%	2527
	11th to 20th	Day	8% 14% 5% 15% 8% 8% 8% 7% 6% 5% 17%	2530
	21st to end	Day	12% 19% 8% 16% 5% 4 4 3 4 7% 18%	2851
February	1st to 10th	Day	9% 12% 5% 10% 5% 6% 5% 5% 4 7% 31%	1710
	11th to 20th	Day	10% 12% 4 9% 6% 5% 4 4 6% 7% 33%	1714
	21st to end	Day	12% 11% 4 10% 7% 5% 6% 4 5% 6% 29%	1570
March	1st to 10th	Day	13% 10% 3 5% 3 4 3 3 4 6% 46%	3120
	11th to 20th	Day	8% 9% 4 10% 6% 5% 4 4 6% 8% 36%	3407
	21st to end	Day	20% 13% 4 11% 6% 4 3 3 4 6% 27%	4086
April	1st to 10th	Day	15% 14% 4 8% 5% 4 4 3 5% 7% 31%	2280
	11th to 20th	Day	20% 11% 3 7% 5% 4 4 3 5% 6% 31%	2254
	21st to end	Day	19% 11% 3 7% 5% 5% 4 4 5% 6% 30%	2364
May	1st to 10th	Day	17% 6% 3 6% 5% 4 5% 3 5% 7% 39%	4399
	11th to 20th	Day	16% 6% 3 6% 3 4 4 3 6% 7% 43%	4399
	21st to end	Day	17% 8% 2 7% 5% 4 5% 4 5% 6% 36%	4824
June	1st to 10th	Day	13% 5% 3 6% 5% 4 4 3 6% 8% 42%	2660
	11th to 20th	Day	15% 7% 3 6% 5% 5% 4 4 6% 8% 37%	2660
	21st to end	Day	12% 6% 3 5% 5% 5% 5% 4 7% 10% 39%	2660
July	1st to 10th	Day	14% 4 2 6% 4 5% 6% 6% 7% 9% 38%	4440
	11th to 20th	Day	6% 3 1 5% 4 4 5% 5% 8% 10% 49%	4440
	21st to end	Day	8% 6% 2 7% 4 5% 4 4 6% 8% 46%	4813
August	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 6% 7% 42%	4408
	11th to 20th	Day	14% 5% 2 5% 3 4 4 4 6% 8% 45%	3948
	21st to end	Day	13% 7% 3 7% 5% 4 5% 4 6% 8% 39%	4180
September	1st to 10th	Day	12% 7% 3 6% 4 3 4 4 6% 7% 45%	2280
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 6% 8% 44%	2248
	21st to end	Day	14% 7% 3 7% 4 3 5% 3 7% 7% 39%	2077
October	1st to 10th	Day	15% 7% 2 6% 4 3 5% 4 7% 7% 40%	1900
	11th to 20th	Day	20% 11% 3 8% 5% 3 5% 3 5% 7% 30%	1830
	21st to end	Day	18% 12% 4 8% 5% 3 3 3 5% 7% 32%	1805
November	1st to 10th	Day	13% 9% 3 7% 5% 4 4 4 5% 7% 39%	1672
	11th to 20th	Day	14% 13% 4 11% 6% 5% 4 3 6% 6% 27%	1583
	21st to end	Day	14% 12% 4 8% 5% 4 5% 3 6% 6% 33%	1520
December	1st to 10th	Day	11% 14% 5% 12% 7% 6% 5% 4 5% 5% 27%	1520
	11th to 20th	Day	13% 16% 6% 10% 7% 6% 5% 4 5% 7% 22%	1918
	21st to end	Day	21% 22% 5% 12% 5% 4 4 3 3 4 17%	2783
January	1st to 10th	Night	11% 14% 7% 12% 6% 4 4 3 4 5% 30%	4428
	11th to 20th	Night	8% 13% 5% 14% 8% 7% 7% 6% 7% 5% 19%	4440
	21st to end	Night	12% 18% 8% 13% 5% 5% 4 4 4 5% 22%	4811
February	1st to 10th	Night	8% 11% 5% 10% 6% 6% 4 3 6% 7% 34%	2470
	11th to 20th	Night	9% 10% 3 8% 5% 5% 5% 4 6% 6% 38%	2352
	21st to end	Night	14% 12% 3 10% 5% 4 4 3 4 7% 33%	1884
March	1st to 10th	Night	10% 7% 3 6% 4 4 5% 3 5% 8% 45%	3733
	11th to 20th	Night	9% 8% 3 10% 7% 5% 4 4 5% 6% 38%	3581
	21st to end	Night	21% 11% 4 12% 6% 5% 4 2 3 4 28%	3544
April	1st to 10th	Night	19% 11% 3 7% 5% 4 4 3 4 7% 34%	1900
	11th to 20th	Night	22% 8% 2 4 4 4 3 4 5% 5% 38%	1875
	21st to end	Night	19% 8% 2 7% 4 4 3 3 5% 7% 37%	1813
May	1st to 10th	Night	16% 9% 3 8% 4 4 4 4 5% 7% 36%	2506
	11th to 20th	Night	14% 6% 2 5% 3 4 4 3 6% 7% 47%	2506
	21st to end	Night	15% 7% 2 7% 5% 4 4 4 6% 7% 40%	2743
June	1st to 10th	Night	13% 5% 2 6% 4 3 4 4 6% 7% 46%	1520
	11th to 20th	Night	11% 5% 2 7% 5% 5% 6% 5% 6% 8% 39%	1520
	21st to end	Night	11% 5% 2 5% 5% 4 4 4 6% 9% 46%	1520
July	1st to 10th	Night	14% 4 2 6% 4 4 4 4 6% 8% 44%	2530
	11th to 20th	Night	5% 4 1 4 3 3 5% 3 6% 10% 56%	2530
	21st to end	Night	7% 5% 2 6% 4 4 4 3 6% 7% 52%	2750
August	1st to 10th	Night	12% 6% 2 6% 4 4 4 4 6% 7% 45%	2517
	11th to 20th	Night	12% 5% 2 5% 3 4 3 3 5% 8% 49%	2886
	21st to end	Night	13% 6% 2 6% 4 4 4 3 5% 6% 44%	3476
September	1st to 10th	Night	10% 4 2 6% 3 4 3 4 5% 6% 53%	1900
	11th to 20th	Night	11% 6% 2 6% 3 4 3 3 6% 6% 50%	1912
	21st to end	Night	12% 7% 2 5% 4 3 4 3 5% 8% 46%	2099
October	1st to 10th	Night	14% 5% 2 6% 3 4 4 4 5% 6% 47%	2280
	11th to 20th	Night	15% 11% 3 7% 4 4 4 4 5% 7% 35%	2203
	21st to end	Night	18% 11% 3 8% 5% 5% 4 4 5% 6% 33%	2550
November	1st to 10th	Night	15% 10% 3 6% 4 3 4 3 5% 7% 41%	2406
	11th to 20th	Night	13% 13% 4 10% 5% 4 5% 4 4 6% 33%	2593
	21st to end	Night	13% 12% 4 8% 6% 5% 4 3 5% 7% 33%	2660
December	1st to 10th	Night	11% 13% 5% 11% 6% 5% 4 4 6% 6% 29%	2660
	11th to 20th	Night	11% 15% 6% 12% 7% 5% 5% 4 5% 6% 25%	3279
	21st to end	Night	23% 18% 5% 10% 5% 4 3 3 4 5% 21%	4884

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	62% 4 10% 18% 6% 1	2528
	11th to 20th	Day	66% 5% 9% 13% 6% 1	2530
	21st to end	Day	67% 3 12% 13% 4	2851
February	1st to 10th	Day	51% 5% 11% 21% 11% 1	1710
	11th to 20th	Day	48% 6% 11% 24% 10% 1	1723
	21st to end	Day	56% 4 11% 18% 10% 2	1570
March	1st to 10th	Day	40% 3 13% 22% 19% 2	3120
	11th to 20th	Day	43% 7% 12% 24% 14% 1	3407
	21st to end	Day	59% 4 8% 20% 7% 1	4086
April	1st to 10th	Day	53% 4 11% 19% 12%	2280
	11th to 20th	Day	54% 5% 8% 20% 11% 2	2254
	21st to end	Day	54% 5% 11% 18% 12% 1	2364
May	1st to 10th	Day	43% 6% 10% 27% 13%	4440
	11th to 20th	Day	40% 5% 12% 31% 12% 1	4403
	21st to end	Day	47% 6% 10% 22% 15% 1	4837
June	1st to 10th	Day	38% 6% 14% 29% 12% 1	2660
	11th to 20th	Day	44% 6% 12% 24% 13% 1	2660
	21st to end	Day	39% 5% 18% 26% 11% 1	2660
July	1st to 10th	Day	40% 7% 16% 27% 9% 1	4371
	11th to 20th	Day	27% 7% 14% 35% 15% 2	4365
	21st to end	Day	36% 5% 13% 28% 17% 1	4662
August	1st to 10th	Day	40% 5% 15% 26% 13% 1	4393
	11th to 20th	Day	36% 5% 13% 34% 12%	3987
	21st to end	Day	43% 6% 12% 28% 11% 1	4179
September	1st to 10th	Day	38% 5% 15% 28% 14% 1	2280
	11th to 20th	Day	36% 5% 19% 31% 8% 1	2248
	21st to end	Day	43% 5% 13% 29% 10%	2077
October	1st to 10th	Day	41% 5% 12% 31% 10% 1	1900
	11th to 20th	Day	54% 5% 12% 20% 8% 1	1830
	21st to end	Day	53% 4 14% 21% 8%	1805
November	1st to 10th	Day	44% 5% 12% 24% 13% 2	1672
	11th to 20th	Day	56% 4 11% 20% 7% 1	1583
	21st to end	Day	51% 4 14% 23% 6% 2	1520
December	1st to 10th	Day	59% 4 12% 20% 5%	1520
	11th to 20th	Day	60% 5% 13% 14% 7% 1	1915
	21st to end	Day	71% 4 7% 13% 5%	2783
January	1st to 10th	Night	57% 4 10% 21% 7% 1	4428
	11th to 20th	Night	63% 5% 10% 16% 6%	4440
	21st to end	Night	65% 4 9% 17% 5%	4811
February	1st to 10th	Night	50% 4 10% 23% 11% 2	2470
	11th to 20th	Night	45% 6% 12% 24% 11% 2	2353
	21st to end	Night	52% 5% 12% 19% 10% 3	1884
March	1st to 10th	Night	38% 4 14% 27% 14% 3	3733
	11th to 20th	Night	44% 6% 10% 25% 14% 1	3581
	21st to end	Night	61% 3 7% 19% 9% 1	3544
April	1st to 10th	Night	51% 4 8% 19% 17% 1	1900
	11th to 20th	Night	46% 5% 9% 22% 14% 3	1875
	21st to end	Night	46% 5% 11% 22% 14% 2	1813
May	1st to 10th	Night	45% 6% 15% 17% 16% 1	2530
	11th to 20th	Night	35% 6% 11% 32% 15% 2	2507
	21st to end	Night	42% 7% 15% 19% 16% 1	2751
June	1st to 10th	Night	36% 6% 14% 30% 14% 1	1520
	11th to 20th	Night	41% 6% 13% 24% 14% 2	1520
	21st to end	Night	34% 6% 14% 31% 12% 3	1520
July	1st to 10th	Night	37% 6% 18% 23% 13% 3	2490
	11th to 20th	Night	24% 6% 15% 37% 17% 2	2482
	21st to end	Night	30% 6% 13% 29% 20% 2	2662
August	1st to 10th	Night	37% 6% 14% 26% 15% 2	2508
	11th to 20th	Night	33% 6% 15% 31% 15% 1	2913
	21st to end	Night	39% 5% 13% 25% 16% 1	3476
September	1st to 10th	Night	31% 5% 12% 33% 18% 1	1900
	11th to 20th	Night	34% 4 14% 35% 13%	1912
	21st to end	Night	36% 6% 12% 31% 14% 1	2099
October	1st to 10th	Night	37% 4 12% 31% 14% 2	2280
	11th to 20th	Night	47% 6% 13% 23% 11% 1	2208
	21st to end	Night	52% 5% 11% 21% 10%	2550
November	1st to 10th	Night	44% 3 12% 24% 15% 1	2406
	11th to 20th	Night	52% 4 14% 17% 11% 1	2593
	21st to end	Night	51% 4 14% 23% 6% 1	2660
December	1st to 10th	Night	55% 4 14% 21% 6%	2660
	11th to 20th	Night	59% 4 11% 18% 6% 1	3281
	21st to end	Night	67% 4 7% 17% 5%	4884

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	16% 13% 31% 27% 10% 3	270
	11th to 20th	Day	22% 11% 36% 22% 7% 1	270
	21st to end	Day	19% 9% 33% 29% 8% 2	297
February	1st to 10th	Day	13% 14% 44% 19% 8% 3	270
	11th to 20th	Day	18% 18% 37% 17% 10%	270
	21st to end	Day	16% 15% 41% 26% 2	225
March	1st to 10th	Day	17% 14% 40% 20% 8%	270
	11th to 20th	Day	18% 12% 39% 19% 9% 3	270
	21st to end	Day	23% 13% 31% 22% 9% 2	453
April	1st to 10th	Day	23% 16% 29% 25% 6% 1	460
	11th to 20th	Day	30% 11% 26% 22% 9% 2	452
	21st to end	Day	24% 13% 30% 21% 10% 3	463
May	1st to 10th	Day	20% 14% 30% 25% 9% 2	653
	11th to 20th	Day	19% 12% 28% 23% 14% 4	675
	21st to end	Day	19% 10% 25% 27% 13% 6%	734
June	1st to 10th	Day	11% 9% 28% 31% 15% 6%	680
	11th to 20th	Day	16% 10% 30% 27% 13% 4	680
	21st to end	Day	13% 9% 28% 29% 14% 7%	680
July	1st to 10th	Day	9% 4 20% 30% 27% 11%	671
	11th to 20th	Day	9% 6% 26% 30% 19% 10%	668
	21st to end	Day	6% 4 27% 30% 24% 9%	739
August	1st to 10th	Day	10% 4 26% 28% 23% 9%	676
	11th to 20th	Day	14% 5% 18% 27% 26% 9%	611
	21st to end	Day	14% 8% 22% 28% 22% 6%	539
September	1st to 10th	Day	17% 6% 25% 24% 22% 7%	490
	11th to 20th	Day	12% 7% 22% 34% 19% 5%	490
	21st to end	Day	18% 8% 26% 28% 15% 5%	477
October	1st to 10th	Day	17% 14% 25% 25% 14% 6%	300
	11th to 20th	Day	22% 20% 28% 23% 6% 1	279
	21st to end	Day	24% 15% 39% 16% 4 1	297
November	1st to 10th	Day	19% 13% 31% 27% 8% 2	270
	11th to 20th	Day	18% 19% 35% 23% 4 1	270
	21st to end	Day	20% 13% 41% 19% 7%	270
December	1st to 10th	Day	15% 11% 44% 21% 9%	270
	11th to 20th	Day	19% 16% 40% 17% 6% 1	270
	21st to end	Day	29% 16% 34% 16% 4	297
January	1st to 10th	Night	15% 11% 37% 28% 8% 1	950
	11th to 20th	Night	17% 11% 37% 26% 6% 2	950
	21st to end	Night	17% 9% 37% 30% 7% 1	1045
February	1st to 10th	Night	13% 13% 37% 29% 7% 1	950
	11th to 20th	Night	14% 12% 41% 26% 7%	878
	21st to end	Night	19% 11% 37% 26% 6%	628
March	1st to 10th	Night	17% 11% 33% 31% 7% 1	760
	11th to 20th	Night	15% 13% 34% 28% 8% 1	632
	21st to end	Night	21% 9% 31% 28% 9% 2	627
April	1st to 10th	Night	23% 10% 34% 25% 7% 1	570
	11th to 20th	Night	26% 8% 32% 27% 7%	563
	21st to end	Night	22% 9% 31% 29% 8% 1	570
May	1st to 10th	Night	21% 10% 32% 29% 6% 1	570
	11th to 20th	Night	20% 5% 31% 34% 9% 1	561
	21st to end	Night	16% 6% 26% 37% 15% 1	617
June	1st to 10th	Night	16% 7% 26% 36% 14% 1	570
	11th to 20th	Night	13% 6% 30% 40% 11% 1	570
	21st to end	Night	13% 5% 22% 42% 17% 1	570
July	1st to 10th	Night	8% 3 21% 39% 27% 3	555
	11th to 20th	Night	9% 5% 23% 36% 25% 3	552
	21st to end	Night	6% 2 19% 46% 24% 3	624
August	1st to 10th	Night	10% 2 20% 43% 24% 2	567
	11th to 20th	Night	14% 2 20% 32% 29% 3	564
	21st to end	Night	15% 4 20% 36% 22% 3	627
September	1st to 10th	Night	12% 3 24% 37% 19% 5%	570
	11th to 20th	Night	12% 4 24% 37% 20% 3	582
	21st to end	Night	14% 8% 29% 31% 16% 2	760
October	1st to 10th	Night	15% 8% 29% 29% 17% 2	760
	11th to 20th	Night	21% 11% 31% 29% 8%	735
	21st to end	Night	22% 10% 32% 26% 9% 1	792
November	1st to 10th	Night	20% 9% 34% 28% 8% 1	740
	11th to 20th	Night	19% 11% 40% 22% 7%	883
	21st to end	Night	20% 13% 35% 26% 5% 1	950
December	1st to 10th	Night	18% 10% 39% 24% 7% 1	950
	11th to 20th	Night	21% 11% 34% 26% 7% 1	950
	21st to end	Night	26% 12% 33% 24% 5%	1045

Page generated at 2024-10-11 09:49:58. Version ac07

Copyright © 2024 Attilla Danko.