Do you know why global warming is the greatest threat to tropical species?

Prof. Know Why answers for your general knowledge and awareness on why global warming is the greatest threat to tropical species:

Global warming is the ultimate concern in today’s world, if you care! Nearly every other day, news headlines are flooded with the topic of global warming, although most of us are probably ignorant about the consequences that global warming can actually cause to living beings.

The latest research on global warming says that while global warming is expected to be strongest at the poles, it may be an even greater threat to species living in the tropics.

Tropical species are accustomed to living in a small temperature range and thus may be unable to cope with changes of even a few degrees, according to an analysis in the last week’s edition of Proceedings of the National Academy of Sciences.

The research was led by Tewksbury, an assistant professor of biology at the University of Washington and Curtis A. Deutsch, an assistant professor of atmospheric and oceanic sciences at the University of California, Los Angeles.

"There's a strong relationship between your physiology and the climate you live in. In the tropics many species appear to be living at or near their thermal optimum, a temperature that lets them thrive. But once temperature gets above the thermal optimum, fitness levels most likely decline quickly and there may not be much they can do about it," Joshua J. Tewksbury said in a statement.

Concern over global warming has largely focused on arctic species like the polar bear. But such animals may be accustomed to living in a wide range of temperatures, while there tends to be little change in the tropics, so there has been no need for species there to adapt.

"The direct effects of climate change on the organisms we studied appear to depend a lot more on the organisms' flexibility than on the amount of warming predicted for where they live," Tewksbury said. "The tropical species in our data were mostly thermal specialists, meaning that their current climate is nearly ideal and any temperature increases will spell trouble for them."

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• Do you know why does the wind blow?
• Do you know why lightning happens?
• Do you know why the sky is blue?

Do you know why does the wind blow?

Prof. Know Why answers:

What is wind? Why does the wind blow? How is wind different from air? Did any of these questions ever struck your mind? - If yes, just read on.

Wind is moving air and is caused by differences in air pressure within our atmosphere. Air, under high pressure, moves to the areas of low pressure. The greater the difference in pressure, the faster the air flows, and the stronger is the wind of that place. –That’s the simple explanation.

The atmosphere is composed of air which, is made up of tiny particles of different gases like nitrogen, hydrogen, oxygen, etc. The Sun shines on our atmosphere all the time. But, it heats the surface of the Earth unevenly. As a result, it’s warm in some places, while cold in other places. When air gets warmer, its particles spread out. This makes the air lighter, or less dense. So it rises. When air cools, it becomes heavier, or denser, and sinks. As warm air rises, air from cooler areas flows in to take the place of the heated air. This process is called convection and causes air to move. The differential heating of the Earth's surface and the resulting convection is what causes wind on this planet.

Have you ever wondered, how a hot air balloon floats in the air? Well, it applies the same science as that of the wind. Air is heated by a gas flame below the balloon. The air inside becomes hot and lighter or less dense than the cooler air outside the balloon. As the hot air rises, it carries the balloon upward. When the gas flame is turned down, the air cools and the balloon sinks back to the ground.

Wind also plays an important role in determining weather conditions.

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Do you know why flame is multicolored?

Prof. Know Why answers:

Flame color depends on several factors, mainly oxygen supply, generated heat, carbon particles and the burning material with the movement of electrons in the metal ions. Thus all flame colors are not the same and different flames have different colors, like the flame color of a candle is different from the flame colors of a burning wood or a gas burner.

Each flame is multicolored, being mostly blue at the bottom, then orange or yellow and finally black at the top. The blue color signifies the hottest temperature zone of any flame. Since fire needs oxygen to burn, and as the bottom of the flame does not get much oxygen, it is the hottest spot in the flame and is blue in color. The flame gradually cools and changes color as it moves away from its source, because it is exposed to more oxygen. The temperature change causes the color of the flame to turn from blue at the hottest lower portion, to the typical bright yellowish-orange or bright orange color at the upper part. The shade of orange at the upper portion of the flame (where the flame is the coolest) depends upon the material being burned. The product of the burnt carbon, when it has cooled, is black soot, and comprises the top part of the flame.

Now, if we get into a little bit of physics, we will understand the scientific reasoning behind the color of a flame. When a material is heated, the electrons gain energy and jump to a higher level. However, they jump back to their initial level to maintain the stability. For this, each of these electrons releases the excess energy. Each jump involves a specific amount of energy being released as light energy, and each corresponds to a particular color. As a result of all these jumps, a spectrum of colored lines is formed. The color you see is the combination of all these individual colors. The exact sizes of the possible jumps in terms of energy vary from one metal ion to another. This means each ion will have a different pattern of spectral lines, and thus a different flame color.

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• Do you know why we fall in love?

Do you know why we have eyebrows?

Prof. Know Why answers:

People have always wondered why humans have eyebrows! They definitely played an important role in our culture though, in terms of beauty, since long time. We pluck, pierce, color or tattoo our eyebrows to make fashion statements. However, they don't seem to serve any other logical function apart from enhancing beauty - or do they? Well! The answer is yes, though their purpose has lost significance over time as humans evolved.

Eyebrows act as umbrellas for the eyes. The arch-shaped eyebrows help keep our vision clear by diverting rain and sweat away from the eyes to the sides of the face - leaving our eyes fairly dry. By doing so, our eyebrows not only allow us to see more clearly, but also keep salty sweat from burning or irritating our eyes.

Eyebrows have other roles too. Recent researches support these theories of the fact - why we did not lose our eyebrows with evolution. As one of our most expressive facial features, eyebrows help us determine how people are feeling without ever really asking them. In fact, eyebrows help with human communications. Often, you can tell how a person is reacting to something just by looking at the way he moves his eyebrows. High eyebrows usually denote emotions like surprise or happiness, whereas low furled brows usually denote anger or unhappiness. In short, eyebrows are a form of non-verbal communication.

Eyebrows also play a major part in identification. Eyebrows help us to identify and recognize individuals. You can test this theory yourself, by hiding the brows from a known person’s picture of the face – you will notice how difficult it becomes in recognizing the person.

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Do you know why we see a mirage?

Prof. Know Why explains:

A mirage is an optical illusion that occurs due to atmospheric conditions by which reflected images of distant objects are seen. In other words, it’s a refraction phenomena in which the image of some objects appear displaced from its true position.

Mirages form when light rays emitted from a source or reflected off an object are bent, as the path of the light ray crosses air layers of different densities.

Common examples of a mirage are the appearance of water some distance down the highway on a hot summer day and seeing a lake in the desert.

Oasis or viewing a lake in the desert happens when light passes through two layers of air with different temperatures. The desert sun heats up the sand, which in turn heats up the air just above it. The hot air then bends light rays and reflects the sky. So when you see it from a distance, the different air masses colliding with each other act like a mirror. And the desert ahead seems to have become a lake which is actually a reflection of the sky above.

Mirages can be seen almost anywhere – those shimmering heat hazes that appear on the road ahead of you on sunny days, but disappear as you approach are mirages. Again, in the countryside you may seem to see a small lake or a pond near trees or in a field, which is also created by the same concept, i.e. differences in temperature between the ground temperature and the air just above the ground level.

Do you know why we see a rainbow?

Prof. Know Why explains:

Witnessing the history, throughout the ages, mankind has always been fascinated by rainbows. And their arched splashes of color have been the subject of numerous songs and poems, stories and mythology. Even, in the Bible, the rainbow is seen as a sign of God's promises.

What makes rainbows so mysterious is the simple but often puzzling fact that rainbows are light and they exist only in the eyes of the beholder! To unlock this amazing secret of the nature and explore how water and light work together to produce the magnificent colorful work of art, we have to understand a little bit of physics, because that’s what it is – pure science!

You need three factors to work together to see a rainbow. Firstly, the sun must be shining. Secondly, the sun must be behind you, and thirdly, the air in front of you must have water drops in it. When the sunlight enters a water drop, it is refracted, or bent, and reflected out from the drop in such a way that the light appears as a spectrum of colors. Actually, the rays of light bend twice. As they enter the drops, the rays of light bend, then reflect off the back of the drops. Then they bend again, this time while exiting the drops. That's when the light appears before our eyes. Each drop reflects only one color of light, so there must be many water drops to make a full rainbow. You'll see the brightest rainbows when the water drops are large, usually right after a rain shower.

When a raindrop bends light, the light exits the raindrop at an angle of 40 to 42 degrees away from the angle it entered the raindrop. As a result, the only beams of light you see are from raindrops that are 40 to 42 degrees away from the shadow of your head. This gives the rainbow its curved appearance.

Do you know why lightning happens?

Prof. Know Why explains:

In one line, lightning is a bright flash of electricity that is produced by a thunderstorm.

Within a thundercloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of these collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud. Lightning results from the buildup and discharge of this electrical energy between positively and negatively charged areas. Lightning can occur within the cloud or between the cloud and the ground as well. In the second case, this electrical charge strikes around anything that sticks up, such as mountains, people, or single trees.

When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. Once the light is gone, the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!

Remember, lightning is approximately six times hotter than the surface of the sun! So, don’t play around during lightning and always look for a safer place or stay indoors.

Do you know why does it rain?

Prof. Know Why explains:

Let me simplify it first - warm air turns the water from rivers, lakes, and oceans into water vapor that rises into the air. That water vapor forms clouds, which contain small drops of water or ice crystals. When the water vapor in the cloud becomes too heavy, it falls back to the ground as rain or snow.

Now let’s get into a detailed explanation. When warm, wet air rises, it cools, and water vapor condenses out to form clouds. As said above, cloud is made up of small drops of water or ice crystals, depending on its height and how cold is the surrounding air. Height and temperature also determine whether any ‘precipitation’ (Latin for 'to fall from') will be rain or the hail associated with thunderstorms, or the snow, or the sleet and freezing rain.

To form rain, water vapor needs a ‘condensation nucleus’, which can be tiny particles of dust, or pollen, swept up high into the atmosphere. When the condensing droplets that form the cloud get large and heavy enough to overcome the upward pressure of convection, they begin to fall. If the temperature all the way to the ground is above freezing, then, it ‘rains’! And when ice crystals form high up in the cloud, and it's below the freezing point of water all the way down, then you get snow.

Thus, rain and snow are the two sides of the same coin!

Do you know why onions make us cry?

Prof. Know Why explains:

It is not the strong odor of the onion, but the gas that the onion releases when we peel off this member of the lily family, makes us cry.

The onion itself contains oil, which contains sulfur, an irritant to both our noses and to our eyes. Cutting an onion arouses a gas contained within the onion, propanethiol S-oxide, which then couples with the enzymes in the onion to emit a passive sulfur compound. When this upwardly mobile gas encounters the water produced by the tear ducts in our eyelids, it produces sulfuric acid. In response to the caustic acid, our eyes automatically blink due to irritation and produce tears to flush out the sulfuric acid.

Moreover, to rid the eyes of this foreign substance, we instinctively rub our eyes with our hands, while into the act, which again exacerbates the situation, as our hands are coated with the caustic, sulfuric acid producing oil from cutting the onion.

The only remedy to get rid of this pungent, irritating oil of the onion is to boil it, and not to slice it or dice it.

Do you know why the sky is blue?

Prof. Know Why explains:

The atoms of nitrogen and oxygen in the atmosphere separate the sun’s white light into its many colors and scatter them throughout the atmosphere. The wavelength of the blue light scatters better than the rest, predominating over other colors in the light spectrum. This makes the sky appear blue to us on a clear day.

The scientific name for this phenomenon is ‘Tyndall Effect’, more commonly known as ‘Rayleigh Scattering’. This phenomenon describes the way in which light physically scatters, when it passes through particles in the earths atmosphere that are 1/10th in diameter of the color of light. The light spectrum ranges in wavelength from red to violet and since the wavelength of the blue light passes through the particles with greater ease than the wavelengths of other colors of light, the sky appears blue to the naked eye.

The human eye has three types of light receptors, known as cones, located in the retina. The cones are either considered to be red or blue or green, based upon their strong response to light at these wavelengths. As light stimulates these receptors, our vision translates the signals into the colors we see. The skylight stimulates the red and green cones almost equally, while stimulating the blue cones more strongly, resulting in the blue colour of the sky.

Do you know why stars twinkle?

Prof. Know Why explains:

On a clear, dark night, our eyes can see about 6,000 or so stars in the sky. They seem to twinkle, or change their brightness, all the time. The scientific name for this twinkling of stars is stellar scintillation or astronomical scintillation. Stars seem to twinkle when we see them from the Earth's surface, because we are viewing them through thick layers of turbulent (moving) air in the Earth’s atmosphere.

The Earth's atmosphere comprises of layers of gases surrounding the Earth. It’s composed of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, and other gases. These gaseous layers insulate the Earth from extreme temperatures and block the Earth from much of the Sun’s incoming ultraviolet radiation.

As light of a star travels through these layers of the Earth's atmosphere, it is bent or refracted many times and in random directions (it happens whenever it hits a change in density - like a pocket of cold air or hot air). This random refraction results in the star appear to our eyes as twinkling.

Stars would not appear to twinkle if viewed from outer space or from a planet that doesn't have an atmosphere.

Do you know why we suffer from blocked ears?

Prof. Know Why explains:

While travelling by aeroplane or climbing mountains we might have temporary ear blockage, which is not associated with loss of hearing though. This happens due to an imbalance in air pressure. Let’s see how it happens.

Ear comprises of three parts –external, middle and internal ear. And for normal hearing, we need to have proper air balance in the middle as well as the external ear. The ‘hearing mechanism’ works like this: A membrane called Tympanic membrane separates the middle ear from the external ear. The middle ear is connected with the upper part of the Pharynx by a tube called the Eustachian tube. Now, when we breathe in, a portion of the air enters the middle ear through this tube. So to balance the pressure within the ear for normal hearing, some amount of air also enters the external ear through the external auditory canal.

But when in a flight or on higher altitudes, the atmospheric pressure inside the middle ear remains the same, while that on the outside reduces, resulting in a pressure imbalance causing temporary ear blockage.