Hello Everyone,
I'm really excited to have been nominated by @pearlumie to join the weekly trend **what i learnt this week**. I'll like to thank @pearlumie for the nomination and special thanks to @mobbs for being totally awesome and for letting us emulate his trend. I hope i am able to enlighten and pass great information as i share with you all,what i learn every week. Come with me as i lecture you on how amazing the last week has been and the great stuff I've learnt.

### Monday-The Reason The Colour Of The Sky Is Blue.
A clear blue sky is always a delight to the eyes, but have you ever wondered ***why the sky is blue?*** Well I've actually thought about that before and i decided to look it up.

The Sun, which is the closest star to the earth, provides earth with heat and light. The light appears white but it actually consists of many different colours.All different colours of light can be seen in a rainbow or if you pass white light through a prism. When white light from the sun travels through the Earth's atmosphere, it collides with the particles of the air and this causes the different colours of light or wavelength to scatter by different amounts.Blue light, which has a shorter wave length is scattered more than the others.

<center>![turkey-3037299_1280.jpg](https://steemitimages.com/DQmQcJpj1YdfBy2uWzkcXS3pUJZgavYC9tvzCii46HVEq4h/turkey-3037299_1280.jpg)</center>
[Image Source ](https://pixabay.com/en/turkey-autumn-season-nature-3037299/)


So, when the Sun is high in the sky, blue light is scattered in all directions as sunlight passes through the atmosphere and we see the sky as blue.

However, when the sun is close to the horizon at sunset or sunrise; Sunlight from the low Sun has to pass through much more atmosphere before it reaches your eyes. This means most of the blue light has been scattered, leaving just the colour with a much longer wavelength(the red colour).This results in the beautiful reddish colour we see during sunrise and sunset, with an occasional flash of green light.

<center>![harbour-crane-1643489_1280.jpg](https://steemitimages.com/DQmQf14UxCxKpy3oALbW6D2gVvctPRREYb27V7CovVvWn22/harbour-crane-1643489_1280.jpg)</center>
[Image Source ](https://pixabay.com/en/harbour-crane-sunset-sky-clouds-1643489/)


The more physics inclined readers will be wondering why the sky isn't purple; Since purple also has a short wave length. The answer lies in our eyes and how it reacts to light.Inside the eye,there are two types of cells that react to light. The Rods and the Cones. 'Rods' are sensitive to brightness and three types of 'cones' are responsible for detecting colour. The three types of cones are sensitive to lights of certain wavelengths.

The 'blue' cones are more sensitive to blue than violet, so when you look up at the sky, the cones tell your brain you are seeing blue even though there is violet there.

[You can read more here.](http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html)


### Tuesday- Does Rainy Weather Really Cause Joint Ache And Back Pain?
The notion that certain symptoms and weather go hand in hand has persisted for a very long time.***Weather pain*** is a sensation that was noticed by Hippocrates back in 400 B.C. Today, people suffering from arthritis are still complaining about worsening pain before an impending storm, and scientists are still puzzled about why exactly stormy days cause more discomfort than other days.

<center>![images-1.jpg](https://steemitimages.com/DQmPgb4QrVKhzV3b4ABKjFFmAK6f6fPj9yYcHqyWmnrwZtz/images-1.jpg)</center>
<center>[Image Source ](https://pxhere.com/en/photo/595159)</center>


A [Source](https://www.psychologytoday.com/blog/health-matters/201410/does-rain-cause-painand-what-do-about-it) online had this to say when i researched:

>When the pressure in the atmosphere is low, clouds and rain are much more likely, and the dampness increases pain and stiffness. One theory on how dampness increases your pain is that the reduction in pressure in the atmosphere allows bodily fluids to move from blood vessels to tissues, causing swelling and pressure on the nerves in those tissues, as well as an increase in fluid in the affected joints. The pressure on the nerves and in the joints would naturally cause increased pain, stiffness and reduced mobility.

A recent research carried out by the George Institute for Global Health has revealed the **weather plays no part in the symptoms associated with either back pain or osteoarthritis.**

The study combined two primary datasets, the first including information on primary care visits for joint or back pain, or both among US Medicare beneficiaries, and the second including detailed information on daily rainfall levels by geographic zip code.
Results showed no association between back pain and temperature, humidity, air pressure, wind direction or precipitation. However, higher temperatures did slightly increase the chances of lower back pain, but the amount of the increase was not clinically important.

[You can read more here for details on the research that proves weather doesn't affect pain.](http://www.bmj.com/content/359/bmj.j5326)

### Wednesday- Polar Bears are nearly undetectable by infrared cameras.

Polar bears aren’t actually white.  Their fur is a series of clear, hollow, translucent tubes which reflect light, making the bear appear white.  It’s the same reason why snow — which is, at its core, crystallized water (and therefore clear) — also appears white.

A polar bear is so well insulated from the cold that it is invisible when photographed with infrared film, which detects heat. Except for a spot in front of its mouth made by its warm breath, the bear gives off no detectable heat for the film to record.

<center>![images-4.jpg](https://steemitimages.com/DQmRUydm6GnN8tZtw4ULvrBGMdKLDkq2VmUCPWVBeK7bVqU/images-4.jpg)</center>
[Image Source ](https://pixabay.com/en/polar-bear-mother-cub-white-arctic-710165/)


The polar bears’ layers of fur and blubber trap their body heat well below their skin, leaving the outer layer to be roughly the same temperature as the snow around them.  The bears’ face and breath can be seen on infrared, but that's about all your going to see. I happen to find this really fascinating by the way!

[You can read more about polar bears and the infared situation Here!](https://www.insidescience.org/news/new-research-reveals-how-polar-bears-stay-warm)

### Thursday-Fresh water Pink Dolphins.
Am sure your wondering... wtf?... pink dolphins? Yes indeed... they are natural pink dolphins and their colour was in no way influenced by man.However, there's a very scientific explanation for the pink surprise.

The dolphins(whose scientific name is ***Inia geoffrensis***) start off gray when they’re young and slowly turn pink as they get older. Their final color can be influenced by their behavior, capillary placement, diet, and exposure to sunlight. The dolphins can be anywhere from mostly gray with some pink spots, to almost flamingo pink. And when the dolphins get excited, they can flush bright pink, similar to humans blushing.

<center>![images-6.jpg](https://steemitimages.com/DQmQFRGN3Ww138jjNboVj4HWu87L5ANwXFAcuvT81LkKAjd/images-6.jpg)</center>
[Image Source ](https://me.me/t/dolphins?s=new)


The culprit for the pink coloured dolphin is***albinism***.Albinism occurs when cells that normally make the pigment melanin, responsible for skin, hair, and eye color, fail to produce it at normal levels, or at all. This is mostly caused by a mutation in several genes.

Two average dolphins both carrying a single copy of the mutation in the same gene; if Combined,those mutations result in the marine mammal's distinctive colour. However, this specie of dolphins is considered vulnerable because it is data deficient, and for it's offspring to be pink, it'll have to mate with another dolphin that has exactly the same gene mutation.This case scenario however, is quite rare.

[You can read more here.](https://en.m.wikipedia.org/wiki/Amazon_river_dolphin)


### Friday- Ninety minutes of sweating can temporarily shrink the brain more than one year of aging does.

Our brains are 80% water. When we fail to replace the fluids lost through sweat, our bodies borrow water from the cells in the brain for use in essential processes elsewhere. This causes the cells in the brain to wither and shrink.

<center>![images-5.jpg](https://steemitimages.com/DQmWSxvJpA7UfPaWsTLXcCnHBXDNS5JsMUczR4onrWRgCW6/images-5.jpg)</center>
[Image Source ](https://www.theepochtimes.com/your-brain-is-shrinking-heres-how-to-reverse-it_1360619.html)


A team of scientists in the UK found that 90 minutes of sweating without replenishing lost fluids shrinks the brain as much as a year of ageing. It also causes withering equivalent to two and half months of Alzheimer’s disease.

<center>![drink-water-.jpg](https://steemitimages.com/DQmPoiRsaUgFVvvKgGEYLHEdUsoCCQsRmbGZhehNqB6wLfn/drink-water-.jpg)</center>
[Image Source ](http://findrugbynow.com/2013/04/optimising-your-hydration-strategy/)


Dehydration not only affects the brain, but also makes it work twice as hard.The good news is these effects can be easily reversed by rehydrating with adequate amounts of fluid.

The bad news is that staying hydrated is sometimes easier said than done. Research suggests that most adults do not consume sufficient amounts of fluid to replace the fluid that is lost each day and that many of us are walking around in a state of perpetual dehydration.

<center>![images.png](https://steemitimages.com/DQmcesM3ThSVkUTmWtRD6VH9qcsYbMnnL5a8t2YKbws93tN/images.png)</center>
[Image Source ](https://www.google.com.ng/amp/s/healthymiranda.wordpress.com/2015/05/14/beware-of-dehydration-it-happens-much-faster-than-you-think/amp/)


Don’t rely on thirst to determine fluid requirements. On average,the thirst response does not kick in until you are 2% dehydrated.Make sure you drink water at regular intervals.
Put in a conscious effort to staying Hydrated.You'll be doing your brain; and eventually yourself... A huge favour.

[You can read more on the research on Dehydration here.](https://www.ncbi.nlm.nih.gov/pubmed/20336685)

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Thank you so much for sticking around!

***And a very Merry Christmas to you and yours!!***

Until my next post, 

Stay Healthy!

@melanie00

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All Image Sources are stated in text!

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**Additional Text Sources:**

1. [Why is the sky blue?](https://www.google.com.ng/url?sa=t&source=web&rct=j&url=http://www.telegraph.co.uk/education/educationnews/11974317/Why-is-the-sky-blue-Childrens-questions-parents-cant-answer.html&ved=0ahUKEwi74trlw6nYAhXiJcAKHUKoARsQFghIMAk&usg=AOvVaw1El1g-vgmSzo_hdloWfp-8)

2. [Myth debunked, rainy weather does not cause back or joint pain.](https://www.google.com.ng/url?sa=t&source=web&rct=j&url=http://www.thejournal.ie/myth-achy-joints-rainfall-3747939-Dec2017/&ved=0ahUKEwi2gu_UxKnYAhVlC8AKHbRUAS0QFggfMAE&usg=AOvVaw3UVLNIqfI2mCgatx_jCRby)

3.  [Why polar bear can't be detected by infrared](https://www.google.com.ng/url?sa=t&source=web&rct=j&url=https://asknature.org/strategy/fur-absorbs-infrared-radiation/&ved=0ahUKEwiLqb6JxanYAhVKL8AKHXX_DfoQFgiGATAX&usg=AOvVaw1QBPnOl6h5V4f_Iciz6kN9)

4. [The pink dolphin ](https://www.sailorsforthesea.org/programs/ocean-watch/plight-pink-dolphin)

5. [Dangers of Dehydration ](http://rehydrate.org/dehydration/)

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