Acacias again

Here are more acacias reflecting in the still waters of Corte Madera Creek.

Food for thought

Rorschach test: is this photo upside-down or right-side up?  Or?

Yesterday on Corte Madera Creek.

Sunrise

Sunrise on Corte Madera Creek with a fog bank in the distance.  You can see it in two places, just lurking.

Tiffany window

These vines on a fence along Corte Madera Creek remind me of a Tiffany window.

Thick fog

Fog was thick on Corte Madera Creek last Thursday.

Bufflehead

Recently we've been seeing a few buffleheads on Corte Madera Creek.  They are migratory and most of them winter in protected coastal waters, or open inland waters, on the east and west coasts of North America and the southern US.  This is why we are seeing them here in California just now.

The Bufflehead is the smallest diving or sea duck in North America. The name buffalo head or "bufflehead" is a direct reference to the duck's large-headed appearance. These ducks are strikingly beautiful. The male is black and white with a large white patch extending from the eye to the back of the head. The female is dark brown above, paler below and has a small white cheek patch. The male is slightly larger than the female.

The Bufflehead is a diver and unlike other diving ducks can take flight from water without having to run along the surface. Buffleheads typically eat aquatic insects, snails, crustaceans and aquatic plants. Buffleheads usually are seen in small groups. As one or two feed, the others will stand watch for potential danger.

Winter tree

Trees in winter can be as beautiful as those in full leaf.  Even though it's January, I think this one is beginning to bud - on Corte Madera Creek.

Whirlpool

Corte Madera Creek (where we see it) is tidal, so sometimes there is a lot of water and sometimes the creek is very shallow.  There are a few pools on the other side of the bike path and they are connected to the creek by culverts under the path.  Last week the tide was going out as we walked the path and saw this whirlpool being created by water draining  the pool through a narrow culvert.  I've always thought that drains in the northern hemisphere flowed in one direction and below the equator in another.  Both Hans and Dick said this is called the 'Coriolis effect'.  However, an article on Wikipedia says that is probably not the case.  If you care to study this, here is the (part of) the article.

Draining in bathtubs and toilets

Coriolis rotation can conceivably play a role on scales as small as a bathtub. It is a commonly held myth that the every-day rotation of a bathtub or toilet vortex is due to whether one is in the northern or southern hemisphere. An article in Nature, by Ascher Shapiro, describes an experiment in which all other forces to the system are removed by filling a 6 ft. tank with water and allowing it to settle for 24 hrs (to remove any internal velocity), in a room where the temperature has stabilized (temperature differences in the room can introduce forces inside the fluid). The drain plug is then very slowly removed, and tiny pieces of floating wood are used to observe rotation. During the first 12 to 15 mins, no rotation is observed. Then, a vortex appears and consistently begins to rotate in a counter-clockwise direction (the experiment was performed in the Northern hemisphere, in Boston, MA). This is repeated and the results averaged to make sure the effect is real. The Coriolis effect does indeed play a role in vortex rotation for draining liquids that have come to rest for a long time. ["Bath-Tub Vortex", Nature. Dec 15th, 1962. Vol 195, No. 4859, p. 1080-1081]

In reality, this experiment shows that the Coriolis effect is a few orders of magnitude smaller than various random influences on drain direction, such as the geometry of the container and the direction in which water was initially added to it. In the above experiment, if the water settles for 2 hrs or less (instead of 24), then the vortex can be seen to rotate in either direction. Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle. If water shot into the basin from the opposite direction, the water would spin in the opposite direction.


The idea that toilets and bathtubs drain differently in the Northern and Southern Hemispheres has been popularized by several television programs, including The Simpsons episode "Bart vs. Australia" and the The X-Files episode "Die Hand Die Verletzt."Several science broadcasts and publications, including at least one college-level physics textbook, have also stated this. Some sources that incorrectly attribute draining direction to the Coriolis force also get the direction wrong, claiming that water would turn clockwise into drains in the Northern Hemisphere.


The Rossby number can also tell us about the bathtub. If the length scale of the tub is about L = 1 m, and the water moves towards the drain at about U = 60 cm/s, then the Rossby number is about 6 000. Thus, the bathtub is, in terms of scales, much like a game of catch, and rotation is unlikely to be important.

Paris?

Hans' coaching (he didn't have his camera along and so he just had to coach) yielded this foggy photo that evokes a Paris street scene.

Creek and path

I often speak of Corte Madera Creek and the bike path along the creek.  Here is a good view of them both; the bike path runs along the other side of the creek as well.  We walk down one side of the creek, cross over Bon Air Bridge and come back along the other side.  It makes a 2-mile loop - a nice morning walk - and often full of surprises!

Culverts in a row

Four culverts in a row on Corte Madera Creek.

Geese in a row

And a lot of geese in a row.

Ducks in a row

Ducks in a row on Corte Madera Creek on Christmas Eve morning

Half Day Cafe

Every Thursday morning after some of us walk on Corte Madera Creek and others run on the College of Marin track, we meet at the Half Day Cafe for breakfast. Sometimes the table swells to 12 or 13 of us and Erica & Kendall give us each separate checks! 

The Half Day has a small entrance on the street and it's only a counter for take-out.  The main restaurant entrance is in the back next to the parking lot. Confusing if you don't know. . .

Orbs

Last Thursday I took a photo of this ditch with the reeds, which flows into Corte Madera Creek.  The photo didn't look the way it appeared to the eye and Hans suggested I try the flash.  That photo came out very dark and I gave up.  However, in Photoshop  I lightened the dark photo and behold! orbs!  I was a bit excited because I have seen such pictures in which some people think the orbs represent souls frequenting certain spots.  ooooooo!

However, the reality is probably a bit more prosaic.  It was a misty day and the flash bounced off moisture drops in the air that were very close to the lens.  Not on the lens, as can be seen in the photo taken seconds earlier, but just close.  For further elucidation see: http://www.ghostvillage.com/resources/2006/features_11092006.shtml

Nest

On the same day that we saw the ladder along Corte Madera Creek, we spied this rare tennis ball nest beside the path.  Strange happenings. . . .

Mystery

Here's a mystery for you - why do you suppose this ladder is standing on the edge of Corte Madera Creek?  It's in the marshy area where no one walks (except the occasional dog). ????

Geese

Last week Corte Madera Creek was teeming with bird life such as these geese (or maybe they're ducks?).

Sweet face

Yesterday at Corte Madera Creek, we had trouble getting any walking done because we were amused by 4 or 5 river otters, playing in the creek. It was hard to get a good shot at them because of plants along the shore, but here's one of a sweet face.

Mt. Tam

Thursday morning the water in Corte Madera Creek was very still. Usually there are some little ripples from the breezes starting about 7 am but this time Mt. Tamalpais in the sun was reflected perfectly in the stream.