If you look at the surface of water at greater than the critical angle (I forget the exact number but around 48 degrees for water), most of the light you see will be a direct reflection of the sky. The greater the angle, the more the light will be reflected. That Wiki section shows this in both pictures, even the first one which ostensibly “manifest[s] water’s inherent blue color.” Almost all the light in that first picture is reflected. You can tell this because the color of the sky changes from being light near the horizon to darker blue higher up. The water color is lighter near the horizon to darker lower down. Furthermore, the sky has some higher clouds on the left making that part lighter and this is reflected in the water color, being lighter on the lower left.
So if you’re on a body of water and you look out over the water, the color is going to be mainly a reflection of the sky. If you look down, the color will be that of the water or impurities within it. If there’s significant waves, you’ll get a mix of the two depending on the exact angle, which of course will be constantly changing. (In fact that second picture has more waves, so the water doesn’t reflect the sky as well as the first one.)
Critical angle is where total internal reflection happens. But that only happens when you are inside a denser (larger index of refraction) medium looking at a boundary with a less dense medium - e.g. you are underwater, looking up at the surface. It doesn’t happen when you are above the air, looking into water.
Reflectivity of water surface (i.e. looking at the water from air) does depend on incident angle, but it’s less than 50% until you are ~85 degrees from normal (i.e. your line of sight is at ~5 degree angle relative to the water surface).
A cold is caused by contracting a respiratory virus.
But cold weather can lower your immune system’s ability to fight infection, and make you more susceptible to contracting a virus. Therefore the advice to stay warm in order to protect yourself from catching a cold is still valid, even if the reasoning behind it is not.
If the transmitted light stayed below the surface, the ocean would appear black. If you can see anything at all when it’s underwater, it’s because some of that transmitted light is being reflected back up (and is undergoing transmission again on the way back up)
I don’t think this has ever been proven. If it were the case, we should see an uptick in all kinds of illnesses during colder months–and we just don’t.
Dinosaurs became extinct (probably a direct result of that meteor that slammed down in the Yucatan) clearing the way for mammals to evolve. Mammals did not cause the extinction.
And thanks to anti-vaxxers, measles season, etc. is back.
This should not be new information to people.
The issues are the factors involved: weather, school in session, people around people more, etc. The belief that cold weather and such doesn’t encourage colds has been challenged quite a bit in recent years.
I’ve never heard anyone claim that mammals caused the extinction of the dinosaurs, and in any case, mammals had already evolved by the event; the removal of dinosaurs allowed mammals to spread, diversify, and dominate.
Thanks for the response. . . Now where in that does it support the point that cold weather depresses the immune system, and where does it show the spike in all other the diseases that you would expect with a depressed immune system ?
Isn’t it also the case that the cold and dry air in winter dries out the mucous membranes which reduces their effectiveness in filtering out airborne diseases? It’s not exactly reducing the immune system’s ability to fight infection, but reducing the pre-screening effectiveness of the upper respiratory system.
In the past it was sometimes suggested that mammals could have contributed to the extinction of the dinosaurs by eating their eggs, or even by competition. (In fact, my first dinosaur book, Roy Chapman Andrews’ All About Dinosaurs (1953), makes these suggestions as a couple among several causes, and the chapter on the extinction is headed by an illustration of couple of ratlike mammals eating a clutch of dinosaur eggs.) And the idea was common in popular culture:
