Sundogs

On our way home from a shopping trip this morning we saw a remarkably bright sundog. Fortunately it persisted for at least 25 minutes so I was able to take some pictures after we arrived home.

10:32

10:48

Later we went for a short walk and saw two more sundogs, both of which seemed to have formed in the contrails of passing planes.

13:01

13:47

All these pictures were deliberately underexposed as the sundogs themselves were so bright that all detail would otherwise have been lost.

Sundogs are also known as parhelia or mock suns. Like halos, they are caused by sunshine on ice crystals in clouds and are seen quite frequently.

You can read more about sundogs, halos and other similar phenomena at the following websites:

http://www.dewbow.co.uk/haloes/sundog.html

http://www.atoptics.co.uk/halo/parhelia.htm
(This site also has software for creating your own haloes)

http://en.wikipedia.org/wiki/Sun_dog

http://hyperphysics.phy-astr.gsu.edu/HBASE/atmos/halo22.html#c3

Senecio rowleyanus

A friend gave us a plant of Senecio rowleyanus (String of beads) recently, and it has been thriving in the sun on our front windowsill.


This plant grows wild in arid habitats, and has spherical leaves to reduce its surface area and help to conserve moisture. (Well... they should be spherical, but apparently I've not been giving mine enough water.) The centre of the leaf contains special transparent cells for storing water. However, this leaf shape is a disadvantage when it comes to photosynthesis, so it has made yet another rather curious adaption. Each leaf has a narrow band of transparent tissue, and this lets light in like a window. The leaf is then able to photosynthesize from the inside as well as from the outside.

Cross section through a leaf:

Soon after it arrived, our plant also produced a rather bizarre flower. Although belonging to the daisy family, this flower has only disc florets and no ray florets and looks more like a little brush than a daisy.

See also:

Senecios with windows in their leaves

Elliott Carter 100

...and don’t forget the American composer, Elliott Carter, who was born on 11th December 1908, one day after Olivier Messiaen. What is more, he is still alive to celebrate his centenary, and still composing prolifically.

Find out more at his centenary website

Events in the UK

Listen to his music - listen to this today! It will be gone in 3 days

Broadcasts