Inanimate Nature
May 19, 2007Public
Photo: Pacific cloudscape, SF->Hnl. 2005.  Can you see the curvature of the Earth?  I almost thought I could.
Photo: Complex cloud system east of Honolulu dropping rain in the center right and with a rainbow added on the top.
Photo: Orographic cloud trails from Maui and Big Island, viewed from near Blowhole, Oahu.   Maui is visible easily.  I half think I see Big Island to its right.  Supposedly, this kind of cloud can help lost sailors find an island they cannot see.
Photo: Cap cloud over Ko'olau mtns, from Manoa
Photo: Lenticular cloud from the Saddle Rd between Maunas Kea and Loa.  It lasted at least 15 minutes but we lost sight of it as we drove along.  The blueness is courtesy of Costco's lacklustre photo development service (yes, this is from my old film camera).
Photo: Lenticular clouds near Kitt Peak, Az, viewed under the arm of the McMath Solar Tower.  The clouds held in position for at least 30 minutes, but changed in form on timescales of a few (5?) minutes.  In the distance I could see many similar, but smaller, clouds.  A bit like giant white UFOs lurking behind the telescope.
Photo: This lenticular spent half an hour at sunset trying to grow in the wind-shadow of a ridge by my house.
Photo: Wave cloud, probably from ripples on the interface between two airmasses.  From the winds and cloud speeds I am guessing that this cloud was about 0.5 to 1 km up and the wavelength was maybe 100 or 200 m, but I don't really know.  Shefford, UK.  The ripples lasted about half an hour before smearing out.
Photo: Rayleigh-Taylor instability traced by cirrus clouds.  This was in the morning, a couple of hours after sunrise, in deepest, darkest Wales.  The clouds mark slightly cooler, denser air that is falling into warmer, less dense air, so making the instability.  The streaks above the mushroom caps show the net motion of the cirrus, downwards in this picture.  This picture is further explained in this paper:
Photo: Low morning clouds, Manoa Valley.  These ones are probably 150m up, adjacent to the west wall.  They just met the rising sun and are starting to evaporate.  Half an hour later they were gone.
Photo: A very wet morning, in the "40 days of rain".
Photo: A very low (100m?) stratus cloud base.
Photo: Volcanic fog ("vog") layer to the east of Mauna Kea, beneath cirrus clouds and above the thermal inversion-capped convective clouds.  The vog is not so white as the water clouds because of sulphur in the droplets.  The inversion at the time of this picture was at 6000ft.  The photo was taken from 14000ft.
Photo: Low ocean clouds and their shadows.  South of Maui from 25000ft.
Photo: Three bands: next to the coast brown = nearly lifeless rock; then  yellow = parched grass; green = living grass.  The clouds tell the story: the land is higher to the left in this image, forced cloud formation there gives rain and shadow protection for plants.  The coast is a desert, too hot and dry for much to grow.  In between, plants grow when they can but are summarily cooked to yellow when the rain fails to materialize.  This is the Waikoloa area on the NE side of Big Island, looking south to Hualalei (whose black flows are visible near the top).
Photo: Sunset from Manoa
Photo: Clouds lit from underneath by the setting sun.
Photo: Oil film on a wet, grooved concrete road surface.  Grooves about 1cm wavelength.  Field width about 2 feet.
Photo: Night rain.  I placed the camera near ground level and shot horizontally.  The light is backscattered from the camera flash.  Exposure is 1/80th second. The region where the drops are in focus is about 0.5m across.  Nearly vertical lines are falling rain. These drops are brighter at the top end, presumably because the flash intensity fades through the duration of the exposure (but maybe there is another reason?).  You can use this to see which way the drops were going: the brightest part marks the start of each trail.  Shorter arcs, many of them near horizontal,  are  droplets splashed up from the ground.  Note the helical tracks.  I think these are either spinning droplets with elongated shapes or drops whose shapes are unstably oscillating just after their formation by impact.  The more obvious helixes have 3 or 4 turns, corresponding to 240 - 320 turns per second (half that if doubly periodic).  Water surface tension is ~0.1 J/m2, giving  maximum spin rate 400/s for droplet radius 0.5mm.  So, consistent.
Photo: Milk foam.   This is back-illuminated through about 5cm of foam.  The yellowy color is from the milk itself.  Cell size is roughly 1 mm.  Here are the cell side counts: (Nsides:Ncounts) = 3:0, 4:2, 5:15, 6:17, 7:5, 8:3, 9:1, 10:1, 11:0. (e.g. 5:15 means I counted 15 pentagons).  I counted shapes in two strips, at the top and bottom, to make it easier.  There's some evidence for a spatial variation in cell size - e.g. the large N cells tend to be at the top. Most surprising is that there are not more hexagons.  And there are no triangles. Why not? Also, if you plot Ncounts as a function of Nsides, the distribution is like a Maxwellian.  Why?  This has to be a minimum energy configuration but my first guess would be that minimum energy would associate with a particular shape (hexagon) and you should see a lot of side-by-side hexagons.  Evidently not.
Photo: Another milk foam picture, this time in B/W and contrast enhanced.
Photo: Caustics in a swimming pool.  Note the colors on the ring.  Field width about 2m.
Photo: Manoa Falls with, to its left, a new channel caused by a rockslide during a very wet 2006.  Erosion in action.  A quick calculation suggests that this is not a dominant mode of erosion in the valley - i.e. Manoa Valley was not primarily excavated by rockslides like this one.
Photo: Here's the "before" picture.  A little misaligned and with a different camera, but the rockslide track is clearly not there.