And now for something yellow

Turmeric stains – a fact that is made clear to me every time I make curry and a drop ends up on my light coloured counter tops (what were the previous owners thinking when they installed baby blue counter tops?). Turmeric seems to stain more than any other spice I use, why?

First, a bit about turmeric. Native to South Asia, turmeric plants thrive in the moist, hot conditions found there. It's a member of a tasty family including: ginger, galangal and cardamom. The name 'turmeric' may originate from the Latin terra merita, which means merit of the earth. The turmeric powder commonly used as a spice is derived from the rhizome, a horizontal stem that typically grows shallow beneath the soil. From this stem, roots and shoots are sent out. These rhizomes are harvested about nine months after planting, then boiled, peeled and dried in the sun. Once dry, it is ground into a power.

About turmeric, Marco Polo said “There is also a vegetable which has all the properties of true saffron, as well as the smell and the colour, and yet it is not really saffron.” In medieval Europe, this spice was called 'Indian saffron' and was commonly used as an alternative to the expensive saffron. According to 'The Flavor Bible' turmeric has a bittersweet pungent flavour. Today it's commonly used to make mustard yellow, and as a component in curries that adds both flavour and colour. At times, turmeric even been used to colour cheeses, margarine and chicken broth. I wouldn't mind at all if turmeric was used as a colourant in my iron pills because it can do some good. In fact, a long list of potential medicinal uses have been attributed to turmeric, one use that has been proven is that it reduces inflammation.

Turmeric's use as a dye probably dates back as long as it's been used. I can't imagine not to noticing that turmeric stains cooking implements once it's added to a dish, however, the first record of using turmeric as a dye comes from an ancient Assyrian herbal recipe dating back to 600 BC (a fact from The Cook's Encyclopedia of Spices). The yellow colour is caused by curcumin, a chemical component of turmeric. About 5% of the dry powder is curcumin. The colouring components of other spices like paprika are less than 1%, so, to answer why turmeric stains more, there is just more colouring potential in the turmeric. On the plus side, turmeric fades in sunlight – so if a drop of curry ends up on a favorite white shirt put it in the sun for the colour to fade.

Can we come up with a better way?

I've been thinking a lot lately about ways I can reduce my ecological footprint and I have some ideas.

I've been reading 'Water, A Turbulent History' by Stephen Halliday, a book I randomly found in the library. I was looking for books on how to improve my house's energy efficiency in the engineering section and I found a history book. I was intrigued by the title so I signed it out. How he describes water pollution by sewage got me thinking.

In 1357, King Edward III decreed 'no man shall take any manner of rubbish, earth, gravel or dung out of his stables or elsewhere to throw and put the same into rivers Thames or Fleet'. Due to this attitude, up until the early 1800's, the Thames and its tributaries remained reasonably clear of pollution.

In London during these times, human waste was removed by dedicated workers called 'nightsoilmen'. These men carted away the waste at night and sold it to farmers as manure. Apparently, they earned a decent pay for their work. Then things changed for the nightsoilmen. Competition was introduced when bird guano was imported from South America, starting about 1840. The guano was easier to work with for the farmers and had less of a smell. About this time, having a water closet in your home became a status symbol.

Water closets were invented in the 16th century by Sir John Harington, who made two. One of which was given to Queen Elizabeth I. She didn't like it because the loudness of the flushing announced to everyone when she used it. Without a royal stamp of approval, the water closet became a neglected idea until early in the nineteenth century.

When a water closet is flushed there is only a little 'waste' for 10-20 times the volume of water. The nightsoilmen found this wet waste hard to collect and transport and the farmers no longer wanted it. Cesspools now overflowed into the waterway, polluting them. Cholera epidemics followed and ultimately sewer systems were built.

So now what was once composted (and likely still is in many parts of the world) is now diluted with water and washed away through dedicated pipes buried beneath the ground by gas guzzling equipment. Sewage ultimately ends up at a dedicated treatment plant of some sort that no one wants to be a neighbour to. At any point a leak could pollute our water ways and in many places this has happened. There must be a solution for urban dwellers that doesn't require fancy infrastructure or lots of a critical resource such as water. I realize human waste can carry disease, but is watering it down and flushing it away the best way to deal with it?

Orange poo and red hats

It's officially a winter day where I live – it's raining. My backyard has turned into a monster mud pit. The sky is gray and everything else ranges from muddy green to brown. But, there is some colour – you just need to look closely. Close to home, the holly bush over my black fence is sporting a few red berries. In the forest there is other colourful natural stuff to be found, even this time of year. Looking through my photos of last winter I found these two colourful gems.

One of my favorites is what I always called 'orange poo'. I remember finding it the woods where I grew up and thinking it was poo of some magical creature. Anyway, by consulting my 'Common Mushrooms of the Northwest' book, I've found it called 'orange jelly' or Dacrymyces palmatus. It's a fungi and apparently edible but not too tasty – I'm not going to confirm this as I have a general policy of not eating wild mushrooms and this particular on is associated with poo in my mind.


If you look closely at a rotting log, you might find a tiny hit of red from the British Soldier lichen or Cladonia floerkeanna (this one I found in my 'Mosses, Lichens and Ferns of the Northwest North America' book). To me this lichen looks like a match.

In general, a lichen is a fungi that is living symbiotically with some sort of alga. Lichens can survive in all sorts of extreme places – some even survived being exposed to outer space for over two weeks (yes, an experiment was conducted on this). Reading the introduction section of my the lichen section of my book it says lichens are used to dye cloth, ferment beer, and in perfumes, lotions and toothpaste – some can even be eaten.


Even on a winter walk, if you observe carefully, there are all sorts of interesting colourful things to see.

I took both photos while on walks last winter

Red moon, blue moon

Based on my recent discussion of blues (colours, not moods), I though I should describe what a blue moon is. 'Once in a blue moon' is a common phrase for an uncommon event. However, the moon is never blue (unless there are smoke or dust particles in the atmosphere, then the moon can appear bluish).

I've seen the moon turn a blood red – a frightening event if I didn't know why it changed colour. On that night it was a lunar eclipse. The earth had moved between the moon and sun, casting the moon into its shadow. Normally, the moon reflects sunlight directly from the sun making it a bright feature in the night sky. When the earth is in the way, the only sunlight to reach the moon is refracted around the earth and as a result the moon takes on a blood red colour (at least it did on the night I watched).

A blue moon is a completly different event, more of a bookkeeping phenomenon. A calander month is on average 30.5 days long, while the time between full moons is 29.3 days. Normally, there is one full moon a month but, on a rare occasion, a month can have two full moons. There are different ways of determining which of the full moons is the blue one. Typically, a season has three full moons, however when one of the months has an extra full moon, the third full moon is condidered a blue moon. This is so rare, a blue moon will occur only seven times in 19 years, which works out to one every two to three years. Mark your calenders as the next one will occur on August 21, 2013.

Been reading 'The Field Guide to Natural Phenomena' by Keith Heidorn and Ian Whitelaw – so far it promises lots of interesting tidbits.

What is it?

I was reading over a paper by John Peyssonel from the Royal Society's Philosophical Transactions (volume 50, 1757-1758, pages 585-589) titled 'Observations on the limax non cochleata purpur ferens, the naked snail producing purple.' It is about some sea creature and after reading it I have no clue what it is.

From the text (which is longest run on sentence I've ever seen):

Among the fish we meet with in the seas of the Antilles of America, we find, that this I am going to describe will appear precious, from the beautiful purple colour it produces, in the same manner, that the cuttle-fish produces its ink, if a means could be found to produce the liquor in a sufficient quantity to render it an article of commerce

The author goes on to describe this 'fish' as soft, viscous, without shells, scales or bones. It has no feet or fins. It acts like a slug when touched, in that it wreaths up as round as it can. In fact, they are so similar to snails and slugs the author calls them 'naked snails.' Their bodies are greenish in colour with black circular spots. They have two horns or antennae which might serve as eyes. Under a tough plate at the back of the body, it keeps a sack of purple juice. The purple juice can be deployed in defense just like a cuttle-fish uses it's ink.

Is this a description of a nudibranch? Or maybe a sea hare?

Where the tidal energy goes

The sun and moon put 3.5 TW of tidal power into the oceans, however, the total amount of energy present ocean-wide remains nearly constant from year to year. There must be a balance between the energy input and output, therefore tidal energy must go somewhere. The energy of the large-scale motions created by tides, along with energy from solar radiation and winds, is successively broken down to smaller scales and ultimately dissipated through viscous forces. This process doesn't happen evenly throughout the ocean, instead close proximity to structural hotspots such as continental shelves and sub-surface topography promote energy dissipation from basin-wide oscillations down to effects measured in millimeters. Complex internal flow dynamics are created at these hotspots which often support unique ecosystems.

Initially, tides are uniform with depth as the pull from the sun and moon act on the entire water column creating wavelengths on the order of thousands of kilometres. As the tide propagates it's molded by the shape of shorelines and roughness of the ocean floor. As it flows onto the shallower continental shelf, bottom friction slows the water down causing energy to accumulate in a smaller volume which acts to amplify the rise and fall of the water. Adding to the complexity of the dynamics, tidal flow over bottom topography produces internal tides (the discovery of which is an interesting tangent for another day). Shear instability, wave-wave interactions and topographical scattering all influence the rate of energy dissipation, and control whether internal tides dissipate near the generation site or far away. Ultimately, all tidal energy dissipates.

When the internal tide interacts with local existing internal waves, the kinetic energy is broken down to smaller scales. Waves are successively subdivided through non-linear processes and turbulence into smaller scale motion. Ultimately, a scale is reached that is small enough that viscosity dominates and the kinetic energy of the fluid motion is dissipated into heat. Effectively, there is an entire range of wave sizes that no longer directly receive energy from tides but are too large for viscosity effects to take hold; these mid-scale waves are called the 'internal subrange' (see my essay on turbulence for more info). In this range, the motion is completely determined by the rate energy enters at the large end of the scale and the rate it dissipates at the small end. In between, energy is transfered by inertial forces alone.

The 3.5 TW of tidal power is first dispersed into internal tides. Through wave-wave interactions and turbulence this energy is ultimately lost in small-scale diffusion. Turbulence is dissipative and irreversible by nature, resulting in kinetic energy lost to molecular viscosity acting on the smallest waves which reappears as thermal energy.

For more info:
Batchelor, G.K. (1953), The theory of homogeneous turbulence, 197pp.

Munk, W. and C. Wunsch (1998), Abyssal recipes II: energetics of tidal and wind mixing, Deep-Sea Research I, 45, 1977-2010.

St. Laurent, L., and C. Garrett (2002), The Role of Internal Tides in Mixing the Deep Ocean, J. Phys. Oceanogr, 32, 2882-2899.

Part 4: Blue Eyes

Here is part 4 of my 4 part series on nature's blues. Part 1 is here, part 2 is here and part 3 is here.

Gaining an understanding why something is the way it is in nature is not always a direct path. We know the blues found in nature are often the result of the object's internal structure rather than pigments, however the actual blue making process can vary. Although the blue of the sky and the blue of a feather can look like the same colour, the actual mechanism involved is very different. The two optical phenomenon involved in making these blues are Rayleigh scattering and coherent scattering. The blues produced either way can look the same.

So, which of these mechanisms is responsible for blue eyes? Rayleigh scattering is the culprit this time. Eyes appear blue when there are only small amounts of melanin present in the iris. Melanin is the pigment that makes the iris brown – a complete lack of melanin results in the pink eyes of an albino. When light passes into an minimally pigmented iris, tiny protein particles in the eye act just like the gas particles in the atmosphere blue wavelengths are preferentially scattered and the eyes appear blue.

As a tangent – here is how Leonardo da Vinci explained blue skies 200 years before Lord Rayleigh:

'I say that the blue which is seen in the atmosphere is not its own colour, but is caused by the heated moisture having evaporated into the most minute and imperceptible particles, which the beams of the solar rays attract and cause to seem luminous against the deep intense darkness of the region of fire that forms a covering among them.'