Category Archives: Views from the mountain

Crepuscular rays from behind

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Leah called me out onto the front porch Tuesday evening right at sunset to see the sky. This is what we saw.

The Sun was setting directly behind us, near the horizon but high enough to illuminate the thunderstorm in the distance. Apparently there were some clouds between us and the Sun, and the shadows of those clouds spread across the entire sky.

Here’s a closer shot at the moon, the clouds and the sky.

The normal view of crepuscular rays is of bright, fan-shaped rays shining out from the Sun through gaps in the clouds. What these images show are the dark areas between the rays. “Normal” crepuscular rays are, as I said, fan shaped, with the narrow part near the Sun, getting wider as you look further from the Sun. These dark “rays” appear wider closer to us, the viewers, and the Sun behind our backs, and they get narrower as they go away from the position of the Sun. How can that be?

Well, my explanation is that the fan-shaped appearance of “normal” crepuscular rays is an optical illusion. The rays are nearly parallel, widening only a small amount. However, they look wider as they get closer to us, just like a road looks wider where your car is and narrower further away. The rays look like they are fan shaped because we tend to see the phenomenon as two-dimensional, as if the rays were pasted on the sky in the far distance. Instead, the rays are actually shining towards us.

This is what we see in these pictures; the rays have shot out from the Sun around the clouds and passed over our heads, disappearing into the distance in the east. Since the rays (or the darker areas between the rays) are very close to parallel, we see them as wider directly overhead and appearing to get narrower as they disappear into the distance. I am not sure I remember seeing this phenomenon before.

If we could have seen the entire dome of the sky, I think we would have seen crepuscular rays appearing narrow at the Sun, wider as they approach and pass over our heads, and then getting narrower again as they shine off into the distance. That would have been a sight.

These rays stayed visible for about a half an hour. I watched as the shadow of the Earth rose up on the bright cloud in the distance until the cloud was a barely-discernible gray mass on the horizon. I thought about the Sun moving towards the west and the shadow climbing up the cloud, and it occurred to me that the Sun was not, of course, moving; it was us. The surface of the Earth was flying at around 860 miles per hour around its axis, at the latitude where we live, carrying us and dragging the entire atmosphere along with it. So it was not the Sun that was moving, gradually hiding the clouds, but the clouds themselves that were retreating from the Sun.

Later Tuesday night that cloud (or one very like it) gave us a show as lightning flashed inside the cloud.

Parade of rainbows

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The remnants of the first named storm of the hurricane season, Alberto, passed to our west on Tuesday, bringing periodic showers. We had already had a lot of rain a few days ago that was not associated with the storm, but with the tropical air mass we have had for some time.

Tuesday evening, there were small, isolated showers passing all around us. We looked out the front door and saw rain falling over town, plus a rainbow. The rainbow dissipated as the shower moved to the north, but it was followed by another shower, and another rainbow. This is a series of images I took as the showers and rainbows paraded by over town.


The rain was falling in bands, so the rainbows themselves were banded.

Although the weather forecasters expected a lot of rain from the storm, we got very little. Fortunately, with the earlier, heavy rain from a few days ago, we have pretty much caught up on precipitation for a while. I have been trying to prepare the furthest reaches of our front yard for planting grass. Now the ground will be far too muddy to work for several days. That’s OK, because I need to do some more work in the house anyway.

Ragged clouds

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We had rain last Saturday night, but it had stopped by Sunday morning, leaving behind ragged clouds high and low over town.

We had some rain Monday, too. It was foggy that night.

This was taken out our bedroom window. That’s our pet maple tree. This was a two-second exposure that I took holding the camera against the window frame.

Rough Ridge Fire

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On Thursday morning we got up and, as usual, I looked out the window to see the sunrise. This is what I saw.

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I wondered why there was a cloud bank with such a clearly-defined edge when there was no passing front at the time. I learned later that it wasn’t clouds, it was smoke coming from the Rough Ridge fire burning in extreme northern Georgia near the Tennessee line. It has been burning since October 16. As of Thursday it had burned more than 10,300 acres. That’s about 16 square miles. The smoke has been blowing down towards the Atlanta area from the Rough Ridge fire and some others.

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The smoke was thick enough that a Code Red air quality alert was issued for the Atlanta area. That means that the particulate matter was high enough to be unhealthy for all people.

The wind direction changed on Friday. This is what the view looked like Friday afternoon.

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Downtown Rome, which is usually visible, is almost completely obscured by smoke. There was a noticeable haze up on the mountain and a slight odor of smoke. I think the thickest part of the plume was east of us; it was not bad, but we were clearly within the plume.

The Rough Ridge fire is burning in the Cohutta Wilderness in the Chattahoochee National Forest. It is thought to have started from a lightning strike. At this point it has not reached populated areas, which is good for residents, but its location in the wilderness area has caused problems for fire fighters. The terrain is rough and the area is isolated.

The unusually warm and dry weather and windy conditions have made fire danger particularly high. The relative humidity has been in the 20-percent range, which sounds to me more like what you might see in the western US.

This Web site has some photographs from the fire.

Atlanta’s air quality was upgraded on Friday to Code Orange, which is unhealthy for sensitive groups. It’s better, but still not good. As far as I can tell, our air quality index is Code Yellow, or moderate.

The weather forecast for Friday night was for more windy conditions. One of the firefighters said in an interview that the fire won’t be completely out until we get a long, soaking rain. There is no rain in the forecast for the next week, so we can expect the fire to continue to burn.

A few new shots

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Last Tuesday when we went downtown for jazz night at a local bar, the moon was close to full. The only camera I had was, of course, the one in my iPhone. This is how the moonrise looked from Broad Street.

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The City Clock is at center. I have mentioned that before. The First Baptist Church is on the right. The large brick building in the center is the old, old Post Office, which also housed the federal court at the time. My father worked for many years in that Post Office before the it moved about two blocks away. He retired from what was then the “new” Post Office. The Post Office moved yet again after he retired. I still like the old, old building.

Here’s a sunrise, this time from our driveway, featuring the twisted old maple tree we saved when we cleared the lot.

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According to our Atlanta TV station, Saturday night was the coldest night since last April. It was not our coldest night, because of this:

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What looks like a vast sea is the top of the temperature inversion from overnight. It got down to around 40F beneath that fog; however, since the winds had died down and it was clear, our low up on the mountain was 51F.