In a previous post I wrote how the North American Monsoon (NAM) was very late getting started in July. Fortunately, once started, it resulted in normal precipitation amounts for the month of August. Here are photographs and discussion of some of the events during the month.
Another SpaceX Falcon 9 was launched from Vandenberg SFB during the evening twilight hours (07 August 2023). And this one might have been even more spectacular than the previous launch (19 July 2023).
The rocket exhaust is beautifully illuminated by the light of the Sun–which is well below the horizon. Next, the rocket moves through the ionosphere and a red glow develops. From the SpaceWeather.com site:
“This is a well studied phenomenon when rockets are burning their engines 200 to 300 km above Earth’s surface,” says space physicist Jeff Baumgardner of Boston University. Some rocket engines spray water (H2O) and carbon dioxide (CO2) into the ionosphere, quenching local ionization by as much as 70%. The F-layer of the ionosphere is particulary effected. Oxygen ions (O+) in the F-layer are hungry for electrons, which they readily steal from the rocket’s exhaust. Captured electrons cascade down the oxygen atom’s energy levels, emitting red photons at a wavelength of 6300 Å–the same color as red auroras.
The exhaust and red glow were bright enough to be reflected in the waters of Lake Mary.
Time lapse of the launch of the SpaceX Falcon 9.
The next launch of a Falcon 9 is scheduled for much later at night and will not be as well lit as this launch.
The North American Monsoon (NAM) has been slow to get started this year. A general rule of thumb is it gets going around the 4th of July and is considered late (but still normal) by mid-July. Likewise an early start can occur as early as mid June–as it did last year.
During the month of July the GFS weather forecast model consistently showed the NAM getting started “Real Soon Now.” But the target was always several days away. Finally, late in the month the rains arrived as an inverted trough (IVT; def. 2) moved across Arizona.
There have been some photogenic storms. A little over a week ago I traveled to the South Rim of Grand Canyon hoping to get some lightning. Although there were some flashes they were far away. On the other hand, the sunset was pretty good. A band of clouds just above the horizon effectively blocked the Sun at my location while beams of light were getting under the clouds and into the canyon farther to the west. The alternating beams of light and shadow were pretty nice.
The following day I went to Wupatki National Monument in hopes of lightning and rainbows. There was a late afternoon storm that moved towards the Monument and produced a lot of lightning. As it got closer it weakened but was still dropping rain and a short time later a beautiful, full double rainbow appeared. All I needed to do was position myself so that I could get the rainbow arch to frame Wukoki Pueblo.
Time lapse of convection developing over the San Francisco Peaks with Marshall Lake in the foreground.
A new storm formed to my southeast as twilight came on and began to produce a lot of lightning. This was the 3rd act of the day and it was a good one.
Later in the week I took a short drive to Marshall Lake near Flagstaff to time lapse the early stages of convection over the San Francisco Peaks–and with some reflections in the waters of the lake. A few lightning bolts landed near the peaks adding to the show.
A few more trips to Grand Canyon rounded out the month.
And, now, the monsoon is on hiatus again.
A few days ago the waxing crescent Moon joined the planets Mercury, Venus, and Mars in the evening sky. A few clouds and the reflection of the evening sky in the lake added a bit of color to the scene.
Afterwards, I stayed around to watch the rocket launch described in the previous post.
Over the years there have been some rocket launches from Vandenberg Space Force Base (SFB) that have been spectacular even when viewed from here in northern Arizona. This requires that the launch occur during twilight. During the day the bright sky overwhelms the faint light of the launch; at night there is no light other than the glow from the rocket engines.
At twilight the sky is dark but as the rocket rises higher it is lit by the Sun and the exhaust gases from the rocket engines are illuminated. Twilight launches do not occur often so being able to see one is an infrequent event. Also, clouds can obscure the view reducing the number of times that one can see these events.
Last night–after a one-day reschedule owing to an abort at T-5 seconds–SpaceX launched a Falcon 9 rocket into the sky from Vandenberg SFB at 2109 MST. The end of astronomical twilight was at 2120 MST in Flagstaff (and 2154 at Vandenberg) so there was reason to expect a good show as the rocket rose out of darkness and into the twilight-illuminated sky.
It was a good show. It took a few minutes for the rocket to rise above the western horizon and into the light but once that occurred it was easy to see. The rocket was visible until 2115 and then was blocked by distant clouds. After it was gone, the glowing exhaust gases remained visible for a few more minutes then faded quickly.
An explanation for the red glow can be found at SpaceWeather.com.
Edit: Added more photos and a link to SpaceWeather.com