Pileus (Latin for cap) cloud. Unlike the mountain cap cloud the pileus is essentially an accessory cloud, that appears as a smooth cap, or hood above a cumulus or cumulonimbus cloud. The cap forms when a humid layer is lifted to its dew point above a rising thermal. This may later penetrate the pileus, which will eventually be absorbed into the main cloud body. Sometimes several layers of pileus form above one another.
Cap cloud or cloud cap is a stratiform, orographic cloud that hovers above or over an isolated mountain peak, formed by the cooling and condensation of moist air forced up and over the peak and lenticularly shaped by horizontal upper level winds. The cloud appears to remain essentially stationary. (
http://www.weatheronline.co.uk/reports/wxfacts/Cap-cloud.htm)
The photos were all taken the morning of 9 MAY 2015.
They are in chronological order and represent basically the same cloud structure crawling southbound across the Catalina Mountains.
The upper winds were were northerners and the ground layer winds were westerners
Some people have asked me to include more technique which I am happy to do.
In this series of photos I had the common problem of the sun to my face instead of my back.
In most of the photos the sun is within 20° of the subject clouds which is definitely close enough to overexpose the photo.
With sun that close the sun's light will hit the bottom of the lens and bounce around like a BB from a Red Rider BB gun with a compass in the stock and this thing which tells time.
Even a great hood has trouble controlling the extra light which just crushes the exposure.
My solution - create a light box of sorts...
In this case the exterior temperature was close enough to my interior house temperature I could not discern any heat waves.
So with the window open and the screen removed I back up about 5-6' from the window.
I adjusted the horizontal blinds until they completely covered the sun but allowed a view of my composition.
I was then able to concentrate on the light solely from the landscape
