On being the largest

I have no idea how it feels to be the largest flower on earth. You will have to ask that to Rafflesia arnoldii. But I definitely know how it smells: like rotting flesh. Yuk! Growing up to 3 ft, there are lots of things that are weird about this plant or should I say flower. For, all that this one seems to have is a flower. No sign whatsoever of stems, leaves (No photosynthesis! Wasn’t it a defining characteristic of being a plant? Got to go back to my 5th std book and make changes) or true roots.



This one belongs to a group of plants called Rafflesia, all of which are parasitic, an endoparasite (grow within the host) to be specific. They specifically parasitize on a member of grape family called Tetrastigma. Rafflesia grow inside the grape plant’s stem penetrating its tissue through a thread like thing called haustorium (Seen in parasitic fungi as well) and absorb all nutrient from it (its like… u make the food, I will put a pipe and suck it out and use it to grow 3ft. Too much of an extravaganza for a parasite).
Once in a while, they put out a bud and after months it flowers, which lasts for few days (~7days). The plant (Rafflesia arnoldii) is unisexual (some species of Rafflesia are bisexual too), so there is a male and female version of the big stinker. Ahh! Now I guess I understand why it stinks! To reproduce it has to pollinate and for that it requires pollinators like flies. And rotting flesh attracts flies. Off comes a fly expecting a feast and Rafflesia sticks its pollens onto its carrier, which unknowingly will transfer the pollen to a female flower. Ingenious! But means by which its seeds are distributed isn’t known for sure, but seems like some shrews eat its fruit (doesn’t that stink?) and thus disperse its seed.

For all this planning and parasitizing, the plant is highly endangered. Blame it on habitat encroachment by humans. That apart there are lots of stuff about Rafflesia that makes them more prone, starting from their requirement of specific host (habitat specificity, occur only in the rainforests of Sumatra and Borneo in the Indonesian Archipelago). Being unisexual, it’s important that the male and female flowers be close by and that they should open around the same time. And to add to it, they flower only for few days, a time constraint as well. What sort of conservation do you think will work out for this flowering giant? (Grow the grape and put some flies and Rafflesia seeds!). Of so many bizarre designs that nature has come up with, Rafflesia arnoldii, is definitely one.

References:
http://www.parasiticplants.siu.edu/Rafflesiaceae/Raff.arn.page.html
http://en.wikipedia.org/wiki/Rafflesia_arnoldii

Dance of light

Through the vast sky she flies, spreading her light ; green ,blue, red, yellow and pinkish hue and the night sky becomes a play of light . She is “Aurora” the Roman Goddess of dawn blessing and bringing the night sky to life.

Well its not some divine glow lighting up the sky around the polar regions although it was believed so, It is Aurora Borealis( Boreas greek for ‘north wind’) in northern hemisphere and Aurora Australis (latin for 'of the south’) in the southern hemisphere. They are brought about by the solar wind particles(more on solar winds in the next post on Coronal Mass Ejection) colliding with the particles in the earth’s upper atmosphere exciting them .The excited particles relax by transferring their energy to others and/ or emitting a photon. Check out these beautiful pictures taken from places like Alaska and North Canada

And Aurora Australis captured by NASA's IMAGE satellite:

Although its occurs everywhere, being a phenomenon of upper atmosphere, it is more clearly visible as one goes farther away from equator and during equinoxes ( guess the reason!)

So what exactly happens when there is collision of solar wind particles with the atmosphere? It either ionizes or excites the oxygen and nitrogen atoms in the atmosphere(the two most common elements in the atomsphere). So if a nitrogen atom is ionized, on getting back an electron it emits blue light.

If it had just got excited, it emits red light and comes to its normal ground state.

The colour of light when an excited oxygen atom comes back depends on its initial excitation and the time it takes to come back to ground state. Green light is given if it comes down within three quarters of a second; red if it takes more time. If it gets to collide some neighboring atom and transfer its energy then none at all.

Do u think the colour is going to be altitude dependent? ( No, not your altitude , I mean the atom’s)

Auroras aren’t restricted to Earth. Solar wind and the planet’s magnetic field brings about a similar recreation of what we observe on earth. This ones from Jupiter:

I leave you gaping with these youtube video. May be try living the moments that we , near the equator don’t get to see.

References:

http://en.wikipedia.org/wiki/Aurora_%28astronomy%29

Now you see it! Now you don't!

Driving through a highway on a hot afternoon, you would have seen water appear from nowhere on the road and then disappear as soon as you came close by.

Highway Mirage

You would have heard stories of how people traveling in deserts see water, when there is none in reality. Sometimes during sunrise or sunset you would have observed a flattened surface of sun near the horizon giving you an impression as if one more sun was coming from below like the following picture:

Inferior Mirage

All the above mentioned observations are due to an optical phenomenon called Mirage.
What is a mirage? Why do you see a mirage of water? Why not ice cream or chocolates? What are the types of mirages?

Let’s try finding out.

Mirage is the image of distant object which is displaced (formed away from where you would expect it, if it were simple reflection) by bending of light rays. The bending of rays is due to a phenomenon you would have heard of called refraction. Try doing this at home to figure out what refraction is: take a glass of water and put a straw in it , you see the straw appearing broken or thicker than the portions above water.

Similar to the bending that happens when light travels from one medium to another( from air to water in above example), changes in the density of a medium also causes light rays to bend.
On a hot day, when the air around the surface the road is hotter than air above it, refraction occurs. The water you see in the case of highway is actually the image of the sky .This is also why one sees water in deserts. Look at the picture below to see what happens to the light rays and what image forms on your eyes.

But why do we see water and not just the image of the sky? Why not ice cream or anything else. Well, because of the displacement of light rays the image of sky is formed on road. Now you can’t just see reflection of sky on a road (without water or mirror on the surface) , so it is your brain that perceives it as water to account for the appearance of sky on a road! So you will see only stuff whose presence you can logically account for.

This type of mirage is called inferior mirage. Inferior implies the image is below the actual object/sky. And this type is very much unstable as the hot and cold air keep mixing, the gradient keeps changing so the inferior mirage may keep moving its position or appear wavy or just vanish.

Another type of mirage is the superior mirage, and yes! As you would have figured out the image appears above the object! Extending the above funda to form a superior image the air below the line of sight must be cooler than above (a phenomenon called temperature inversion). So opposite to that of inferior mirage in this one the light ray is bent down and hence you get image above. So where would you find such temperature inversion frequently? In polar regions of course just above the ice sheets (and sometimes around the shorelines). And such mirages are stable! Cold air doesn’t rise up so the image stays longer.

Superior mirage come in different types depending on the density structure of the air: Towering(object appearing to be stretched as well as elevated), looming (objects appear to float above the horizon), inversion(inverted image and also the upright actual object is seen).The ray diagrams below explains the ways light bends creating the different superior mirages:

Towering superior mirage

Inverted superior mirage

Looming superior image

Superior mirage can make you see the sun before it has actually risen up (Novaya Zemlya effect) and far away ships appear at horizon or above the horizon. History has it that way back in 1596 the crew of an ill fated ship on an expedition to Polar Regions (where it got stuck at a place called Novaya Zemlya) saw a distorted sun rise in between a winter night weeks before it should! No one ever understood why it happened till late 20th century. Novaya Zemlya effect occurs when there is a huge temperature gradient (up to 400km ). The sunlight is bent to the earth’s curvature (to a minimum of 400km) that causes an elevation of 5 degrees of the sun disk. So sun appears in the sky long before it should.

Think about this: Had earth been flat, would you still see these mirages?

Another very complex type of mirage is the Fata Morgana. It is an ever changing mirage occurring as a combination of superior mirages and sometimes quickly fluctuating between superior and inferior types. The name Fata Morgan or Morgan le Fay is the name of a powerful sorceress and shape-shifting half sister of King Arthur, legendary British leader

This also commonly occurs in Polar Regions but may be seen in deserts and over ocean on a hot climate. For a Fata Morgana to occur, strong temperature inversions are required so that the light ray curve (within the inversion) more than the Earths curvature itself!

Fata Morgana :The arrow in the image on points the real boat. Apart from that you can see two more.

Mirages also occur for astronomical objects like the sun, moon, comets and planets. Below is the inferior image of Comet McNaught:

Thus, a simple play of light and perception of what is observed by the eye, gives rise to all the above mentioned optical phenomena called mirage.

References:

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

http://mintaka.sdsu.edu/GF/mirages/mirintro.html