Stone Mountain State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stone Mountain State Park clear sky chart from 2005-11-06 to 2024-11-04.

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	15% 6% 2 6% 4 4 5% 4 6% 8% 41%	101205
	Night	16% 6% 2 5% 4 4 4 3 5% 7% 44%	97767
Transparency	Day	38% 8% 12% 21% 16% 5%	104895
	Night	37% 7% 11% 22% 17% 5%	102216
Seeing	Day	18% 11% 22% 24% 17% 7%	15215
	Night	17% 8% 23% 30% 19% 3	25280

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	17% 4 1 4 3 3 3 3 4 6% 53%	2836
	11th to 20th	Day	15% 6% 2 6% 4 3 3 3 4 5% 49%	2840
	21st to end	Day	25% 5% 2 5% 3 3 3 2 4 4 44%	3124
February	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 6% 7% 43%	1710
	11th to 20th	Day	18% 8% 2 5% 4 4 4 3 5% 6% 42%	1796
	21st to end	Day	19% 7% 2 4 4 3 5% 4 5% 6% 40%	1598
March	1st to 10th	Day	25% 6% 1 5% 3 3 3 4 5% 6% 40%	3435
	11th to 20th	Day	12% 5% 2 4 3 3 4 3 5% 7% 53%	3480
	21st to end	Day	22% 7% 1 5% 3 3 3 3 5% 7% 41%	3815
April	1st to 10th	Day	11% 5% 1 4 4 3 4 3 7% 8% 50%	2095
	11th to 20th	Day	16% 5% 2 5% 4 4 4 3 6% 7% 45%	2254
	21st to end	Day	15% 6% 2 5% 5% 5% 5% 4 5% 7% 42%	2465
May	1st to 10th	Day	15% 7% 2 6% 6% 5% 6% 4 7% 8% 34%	4082
	11th to 20th	Day	20% 6% 2 7% 4 5% 5% 4 7% 8% 32%	4081
	21st to end	Day	10% 5% 2 5% 5% 5% 5% 5% 7% 10% 42%	4476
June	1st to 10th	Day	12% 6% 2 6% 5% 6% 6% 5% 8% 9% 34%	2470
	11th to 20th	Day	10% 5% 2 7% 6% 6% 6% 5% 7% 11% 36%	2470
	21st to end	Day	9% 5% 2 6% 6% 6% 6% 6% 9% 10% 35%	2470
July	1st to 10th	Day	8% 5% 2 7% 6% 6% 7% 6% 9% 10% 35%	4120
	11th to 20th	Day	9% 6% 3 7% 5% 7% 7% 7% 8% 10% 31%	4120
	21st to end	Day	15% 8% 3 10% 7% 8% 8% 6% 7% 8% 22%	4466
August	1st to 10th	Day	15% 8% 3 8% 5% 6% 6% 5% 8% 10% 26%	4104
	11th to 20th	Day	9% 6% 2 7% 5% 6% 6% 5% 8% 11% 34%	4044
	21st to end	Day	7% 4 2 5% 4 5% 5% 4 6% 10% 49%	4286
September	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	2136
	11th to 20th	Day	18% 6% 2 6% 4 5% 4 3 6% 8% 37%	2090
	21st to end	Day	22% 7% 2 5% 4 4 5% 3 5% 6% 36%	2090
October	1st to 10th	Day	17% 4 2 5% 3 3 3 3 4 5% 52%	1968
	11th to 20th	Day	15% 4 2 4 3 3 4 2 4 5% 54%	1900
	21st to end	Day	15% 4 2 5% 3 2 3 2 4 5% 55%	2090
November	1st to 10th	Day	13% 5% 1 5% 3 3 3 2 4 5% 56%	1887
	11th to 20th	Day	13% 4 1 3 3 3 4 3 5% 7% 54%	1710
	21st to end	Day	15% 5% 1 5% 4 3 2 3 5% 7% 51%	1710
December	1st to 10th	Day	18% 8% 2 6% 4 4 4 3 4 6% 39%	1710
	11th to 20th	Day	14% 5% 2 3 2 3 3 3 5% 6% 54%	2153
	21st to end	Day	22% 6% 2 4 3 3 4 4 5% 7% 40%	3124
January	1st to 10th	Night	16% 6% 2 4 3 3 4 3 5% 6% 49%	4109
	11th to 20th	Night	15% 6% 2 5% 3 3 4 3 4 6% 49%	4120
	21st to end	Night	25% 7% 2 3 3 3 3 3 4 5% 43%	4532
February	1st to 10th	Night	14% 7% 2 4 4 5% 4 4 6% 6% 45%	2470
	11th to 20th	Night	20% 6% 2 5% 4 2 4 3 5% 5% 44%	2268
	21st to end	Night	16% 6% 2 6% 4 4 4 4 6% 6% 41%	1854
March	1st to 10th	Night	26% 9% 2 5% 3 3 3 4 4 5% 36%	3418
	11th to 20th	Night	10% 3 1 4 3 3 5% 3 5% 7% 56%	3480
	21st to end	Night	18% 6% 2 4 3 3 4 4 6% 7% 44%	3817
April	1st to 10th	Night	13% 6% 2 4 4 4 4 3 6% 7% 47%	2083
	11th to 20th	Night	16% 5% 2 4 4 3 4 3 5% 8% 47%	1875
	21st to end	Night	15% 5% 2 4 3 3 4 3 5% 7% 48%	1729
May	1st to 10th	Night	16% 8% 2 6% 4 4 4 4 5% 8% 40%	2813
	11th to 20th	Night	20% 7% 2 5% 4 4 3 3 5% 7% 40%	2812
	21st to end	Night	12% 4 2 5% 4 3 4 4 8% 11% 45%	3079
June	1st to 10th	Night	11% 5% 2 5% 5% 5% 5% 5% 8% 10% 41%	1710
	11th to 20th	Night	12% 6% 2 5% 3 4 4 3 7% 10% 43%	1710
	21st to end	Night	8% 5% 2 5% 5% 5% 5% 4 7% 12% 42%	1710
July	1st to 10th	Night	10% 5% 2 6% 5% 4 4 6% 8% 10% 38%	2840
	11th to 20th	Night	9% 5% 2 6% 5% 5% 5% 5% 9% 10% 39%	2840
	21st to end	Night	13% 8% 3 9% 7% 6% 6% 5% 7% 9% 27%	3087
August	1st to 10th	Night	16% 8% 3 8% 5% 4 5% 5% 7% 10% 29%	2825
	11th to 20th	Night	12% 7% 2 8% 5% 5% 5% 4 7% 9% 37%	2785
	21st to end	Night	7% 4 1 4 4 4 4 4 6% 8% 52%	3338
September	1st to 10th	Night	12% 5% 2 6% 5% 4 4 4 6% 7% 45%	2040
	11th to 20th	Night	18% 7% 3 6% 4 3 4 3 5% 7% 39%	2090
	21st to end	Night	22% 6% 2 5% 4 4 5% 3 5% 5% 39%	2090
October	1st to 10th	Night	16% 6% 2 6% 3 2 3 3 4 6% 48%	2210
	11th to 20th	Night	16% 5% 1 4 3 3 3 3 4 6% 54%	2280
	21st to end	Night	15% 4 1 4 3 3 3 3 4 4 57%	2508
November	1st to 10th	Night	16% 5% 2 4 3 3 3 2 3 5% 55%	2264
	11th to 20th	Night	15% 4 1 3 3 3 3 3 4 6% 55%	2467
	21st to end	Night	14% 6% 1 5% 3 2 4 4 5% 6% 51%	2470
December	1st to 10th	Night	19% 6% 2 5% 4 3 4 3 4 5% 44%	2470
	11th to 20th	Night	16% 5% 2 4 3 3 3 2 4 6% 50%	3042
	21st to end	Night	24% 6% 2 4 3 4 4 3 6% 6% 38%	4532

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	33% 4 7% 27% 22% 8%	2837
	11th to 20th	Day	37% 4 7% 18% 29% 5%	2840
	21st to end	Day	43% 4 6% 21% 22% 5%	3124
February	1st to 10th	Day	39% 6% 11% 22% 18% 4	1710
	11th to 20th	Day	41% 4 9% 20% 20% 6%	1806
	21st to end	Day	43% 7% 11% 16% 17% 6%	1598
March	1st to 10th	Day	44% 4 9% 21% 14% 8%	3435
	11th to 20th	Day	30% 6% 8% 23% 21% 11%	3480
	21st to end	Day	43% 4 8% 24% 17% 4	3815
April	1st to 10th	Day	30% 6% 13% 24% 21% 6%	2095
	11th to 20th	Day	36% 6% 11% 19% 20% 7%	2254
	21st to end	Day	39% 8% 12% 23% 15% 3	2465
May	1st to 10th	Day	44% 11% 13% 19% 12% 2	4120
	11th to 20th	Day	46% 10% 11% 22% 10% 1	4085
	21st to end	Day	33% 10% 18% 21% 16% 3	4489
June	1st to 10th	Day	40% 11% 16% 22% 10% 1	2470
	11th to 20th	Day	38% 11% 16% 19% 14% 2	2470
	21st to end	Day	37% 12% 16% 19% 14% 1	2470
July	1st to 10th	Day	39% 13% 18% 18% 9% 3	4055
	11th to 20th	Day	41% 12% 22% 18% 5% 1	4051
	21st to end	Day	54% 12% 13% 15% 5% 1	4324
August	1st to 10th	Day	48% 11% 18% 18% 5%	4091
	11th to 20th	Day	39% 12% 20% 19% 8% 2	4083
	21st to end	Day	29% 8% 17% 33% 11% 2	4286
September	1st to 10th	Day	37% 11% 12% 20% 17% 4	2136
	11th to 20th	Day	42% 8% 12% 20% 16% 2	2090
	21st to end	Day	48% 5% 10% 18% 16% 3	2090
October	1st to 10th	Day	29% 6% 7% 20% 27% 10%	3267
	11th to 20th	Day	23% 3 5% 24% 25% 20%	3140
	21st to end	Day	27% 5% 8% 25% 19% 16%	3428
November	1st to 10th	Day	31% 4 8% 22% 27% 8%	1887
	11th to 20th	Day	31% 4 9% 23% 26% 7%	1710
	21st to end	Day	34% 4 8% 22% 27% 5%	1710
December	1st to 10th	Day	46% 5% 9% 19% 17% 5%	1710
	11th to 20th	Day	31% 4 9% 23% 23% 9%	2150
	21st to end	Day	42% 4 10% 25% 16% 3	3124
January	1st to 10th	Night	34% 5% 10% 22% 23% 6%	4109
	11th to 20th	Night	37% 5% 8% 17% 26% 7%	4120
	21st to end	Night	44% 5% 6% 19% 20% 6%	4532
February	1st to 10th	Night	38% 4 10% 23% 19% 4	2470
	11th to 20th	Night	41% 5% 9% 20% 18% 7%	2269
	21st to end	Night	42% 5% 11% 19% 18% 5%	1854
March	1st to 10th	Night	49% 6% 8% 17% 15% 5%	3418
	11th to 20th	Night	28% 6% 8% 24% 20% 14%	3480
	21st to end	Night	38% 5% 9% 26% 15% 6%	3817
April	1st to 10th	Night	36% 5% 11% 22% 21% 5%	2083
	11th to 20th	Night	35% 6% 10% 22% 20% 7%	1875
	21st to end	Night	36% 6% 12% 27% 17% 3	1729
May	1st to 10th	Night	42% 9% 15% 23% 10% 1	2840
	11th to 20th	Night	44% 8% 13% 24% 10% 1	2813
	21st to end	Night	30% 10% 17% 28% 13% 2	3087
June	1st to 10th	Night	35% 11% 16% 23% 12% 2	1710
	11th to 20th	Night	35% 9% 19% 24% 13% 1	1710
	21st to end	Night	33% 12% 17% 21% 13% 4	1710
July	1st to 10th	Night	39% 13% 16% 19% 11% 2	2795
	11th to 20th	Night	36% 12% 25% 21% 5% 2	2786
	21st to end	Night	51% 12% 14% 17% 5%	2988
August	1st to 10th	Night	48% 10% 19% 17% 5%	2814
	11th to 20th	Night	41% 12% 19% 18% 10% 1	2812
	21st to end	Night	28% 10% 14% 37% 9% 3	3338
September	1st to 10th	Night	37% 8% 15% 20% 15% 5%	2040
	11th to 20th	Night	44% 7% 11% 18% 18% 1	2090
	21st to end	Night	46% 7% 10% 18% 17% 3	2090
October	1st to 10th	Night	35% 6% 7% 18% 23% 11%	3691
	11th to 20th	Night	22% 3 7% 25% 28% 16%	3779
	21st to end	Night	26% 4 6% 23% 25% 15%	4120
November	1st to 10th	Night	34% 4 8% 21% 24% 8%	2264
	11th to 20th	Night	31% 4 9% 21% 26% 9%	2467
	21st to end	Night	33% 4 8% 25% 25% 5%	2470
December	1st to 10th	Night	42% 6% 7% 21% 18% 5%	2470
	11th to 20th	Night	36% 4 9% 18% 24% 9%	3044
	21st to end	Night	44% 6% 12% 21% 17% 2	4532

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	26% 27% 30% 13% 4	270
	11th to 20th	Day	31% 20% 32% 16% 1	270
	21st to end	Day	25% 28% 33% 10% 4	297
February	1st to 10th	Day	23% 24% 30% 19% 3	270
	11th to 20th	Day	33% 25% 31% 10%	270
	21st to end	Day	28% 25% 34% 12% 2	253
March	1st to 10th	Day	21% 20% 30% 20% 7% 1	460
	11th to 20th	Day	22% 23% 31% 18% 5% 1	460
	21st to end	Day	25% 18% 32% 19% 5% 1	506
April	1st to 10th	Day	18% 20% 30% 20% 10% 1	460
	11th to 20th	Day	19% 16% 26% 24% 12% 3	452
	21st to end	Day	20% 14% 27% 25% 11% 4	460
May	1st to 10th	Day	18% 16% 30% 20% 11% 5%	463
	11th to 20th	Day	19% 7% 24% 26% 17% 7%	487
	21st to end	Day	18% 5% 19% 26% 20% 12%	529
June	1st to 10th	Day	12% 6% 17% 36% 20% 9%	490
	11th to 20th	Day	12% 6% 19% 24% 29% 11%	490
	21st to end	Day	11% 3 20% 33% 23% 10%	490
July	1st to 10th	Day	11% 3 12% 26% 31% 17%	485
	11th to 20th	Day	8% 2 13% 27% 32% 18%	484
	21st to end	Day	13% 3 11% 28% 28% 16%	532
August	1st to 10th	Day	17% 3 18% 23% 20% 18%	486
	11th to 20th	Day	13% 2 12% 31% 25% 17%	479
	21st to end	Day	10% 2 9% 27% 31% 20%	539
September	1st to 10th	Day	14% 2 14% 24% 31% 15%	490
	11th to 20th	Day	18% 5% 13% 21% 31% 12%	490
	21st to end	Day	25% 7% 18% 27% 17% 5%	490
October	1st to 10th	Day	21% 6% 15% 27% 25% 6%	490
	11th to 20th	Day	14% 13% 23% 27% 20% 3	490
	21st to end	Day	19% 9% 23% 32% 14% 3	539
November	1st to 10th	Day	21% 10% 24% 28% 13% 3	467
	11th to 20th	Day	16% 22% 29% 24% 7% 1	270
	21st to end	Day	15% 20% 30% 26% 8% 1	270
December	1st to 10th	Day	27% 20% 29% 19% 4	270
	11th to 20th	Day	21% 17% 33% 22% 7%	270
	21st to end	Day	26% 17% 31% 20% 5% 1	297
January	1st to 10th	Night	18% 15% 35% 26% 6%	760
	11th to 20th	Night	21% 12% 34% 30% 3	760
	21st to end	Night	19% 10% 40% 28% 3	836
February	1st to 10th	Night	18% 13% 33% 33% 4	760
	11th to 20th	Night	23% 15% 38% 22% 2	743
	21st to end	Night	18% 15% 38% 27% 2	628
March	1st to 10th	Night	18% 13% 34% 30% 5%	760
	11th to 20th	Night	19% 13% 36% 26% 7% 1	760
	21st to end	Night	19% 12% 33% 28% 6%	836
April	1st to 10th	Night	17% 15% 32% 28% 8%	760
	11th to 20th	Night	18% 13% 27% 30% 12% 1	751
	21st to end	Night	17% 7% 29% 35% 12%	589
May	1st to 10th	Night	15% 10% 28% 30% 17% 1	570
	11th to 20th	Night	18% 7% 19% 34% 20% 2	561
	21st to end	Night	19% 2 12% 29% 33% 6%	617
June	1st to 10th	Night	11% 2 12% 39% 31% 4	570
	11th to 20th	Night	13% 2 13% 30% 36% 5%	570
	21st to end	Night	8% 1 11% 35% 40% 4	570
July	1st to 10th	Night	10% 1 9% 26% 46% 7%	555
	11th to 20th	Night	9% 1 5% 29% 48% 8%	552
	21st to end	Night	9% 1 7% 29% 45% 8%	624
August	1st to 10th	Night	16% 2 8% 28% 39% 7%	567
	11th to 20th	Night	14% 3 7% 31% 38% 8%	564
	21st to end	Night	12% 2 7% 27% 42% 10%	750
September	1st to 10th	Night	13% 3 9% 29% 38% 9%	760
	11th to 20th	Night	19% 3 13% 24% 34% 6%	760
	21st to end	Night	24% 4 15% 30% 24% 2	760
October	1st to 10th	Night	19% 5% 18% 27% 25% 6%	760
	11th to 20th	Night	18% 6% 24% 32% 18% 3	760
	21st to end	Night	16% 10% 19% 38% 15% 2	836
November	1st to 10th	Night	18% 7% 21% 36% 15% 2	755
	11th to 20th	Night	16% 10% 26% 35% 11% 1	760
	21st to end	Night	15% 10% 30% 33% 11% 1	760
December	1st to 10th	Night	23% 10% 31% 29% 8%	760
	11th to 20th	Night	19% 8% 33% 32% 7%	760
	21st to end	Night	27% 12% 24% 32% 5%	836

Page generated at 2024-11-01 22:47:34. Version ac07

Copyright © 2024 Attilla Danko.