The video explores the multifaceted nature of water, focusing on its significant implications in a global context. By examining water's unique properties, like the fact that ice is less dense than liquid water, the speaker delves into how this anomaly impacts ecological systems and the stability of life during cold seasons. This intriguing exploration underscores the vital role of water in regulating ecosystems and maintaining equilibrium within our environment.

Moving beyond the basics, the speaker illuminates the often overlooked vibrancy and color diversity that water exhibits. These phenomena are explained through scientific concepts like selective absorption and refraction, unpacking the reasons behind why rivers appear brown or oceans look blue, and how rainbows form. These insights reveal the remarkable abilities of liquid water in interacting with light, resulting in the beautiful array of colors we observe.

Main takeaways from the video:

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Key Vocabularies and Common Phrases:

1. syllabus [ˈsɪləbəs] - (noun) - An outline of the subjects in a course of study or teaching. - Synonyms: (curriculum, program, outline)

As a physics teacher and writer, my job is to accept and interpret a syllabus.

2. mantra [ˈmæntrə] - (noun) - A statement or slogan repeated frequently; a guiding principle. - Synonyms: (motto, slogan, saying)

The mantra it's all about applying knowledge isn't wrong, but it masks the barriers to reaching this point.

3. privileged [ˈprɪvəlɪdʒd] - (adjective) - Having a special advantage or favor. - Synonyms: (blessed, fortunate, advantaged)

That's why I'm so excited and privileged to be here today, free from grades, to share how we can all physicists or not, rethink what we know.

4. prowess [ˈprəʊɪs] - (noun) - Skill or expertise in a particular area or field. - Synonyms: (skill, expertise, ability)

Norway's hydroelectric prowess is globally renowned powering industries and homes alike.

5. hexagonal lattice [hɛkˈsæɡənl ˈlætɪs] - (noun) - A structure forming a repetitive six-sided shape. - Synonyms: (six-sided arrangement, hexagonal network, grid)

At the molecular level, water molecules arrange themselves into a hexagonal lattice when they freeze, due to attractive so called hydrogen bonds.

6. selective absorption [sɪˈlɛktɪv əbˈzɔrpʃən] - (noun) - The process by which certain wavelengths of light are absorbed by a material. - Synonyms: (specific uptake, targeted absorption, differential absorption)

In this case, what gives water its ability to exhibit these extraordinary colors is, as with earlier, its molecular structure warriors. Iconic blue is a result of a phenomenon known as selective absorption.

7. refraction [rɪˈfrækʃən] - (noun) - The change in direction of a wave passing from one medium to another. - Synonyms: (bending, deflection, deviation)

The answer lies in how water affects light. When sunlight encounters a water droplet, it undergoes refraction that's changing direction as it enters and exits the droplet.

8. resonate [ˈrɛzəˌneɪt] - (verb) - To produce or be filled with a deep, full sound; or to relate harmoniously. - Synonyms: (echo, reverberate, vibrate)

Unlike other substances, greenhouse gases resonate like a mass connected to a spring in the presence of infrared radiation.

9. amplifies [ˈæmplɪˌfaɪz] - (verb) - To increase the strength or intensity of something. - Synonyms: (boost, increase, enhance)

Water vapor, like carbon dioxide, amplifies the greenhouse effect, contributing to the increasing temperatures of our planet.

10. variability [ˌvɛriəˈbɪlɪti] - (noun) - The quality of being subject to change, especially frequent change. - Synonyms: (fluctuation, changeability, inconsistency)

What sets water vapor apart from other greenhouse gases is both its abundance and variability

The physics of water - Dr Emma Mitchell - TEDxUWCRCN

As a physics teacher and writer, my job is to accept and interpret a syllabus, think about what excites me and my classes, convert topics and lists into lesson plans, and hopefully inspire the next generation of scientists, engineers, problem solvers and thinkers. Saying this, I can't help but notice the weight of ever losing assessment. It's not enough to love physics. My students have to get really good at passing physics exams, and physics exams are challenging. The mantra it's all about applying knowledge isn't wrong, but it masks the barriers to reaching this point. There are hundreds of facts to be memorized, dozens of equations to manipulate, countless abstract contexts from which questions can be formed, and highly specific techniques to adopt in order to be marked correct. It's quite thrilling when you find it fun, but difficult to penetrate in vault. Maybe you do or don't study physics today for this exact reason.

That's why I'm so excited and privileged to be here today, free from grades, to share how we can all physicists or not, rethink what we know. Our topic today is a familiar one. If I do my job as a speaker, well, you'll notice the peculiarities of this familiar idea and maybe even appreciate the scientific reasons that lie behind them. This topic water in a global context. As the saying goes, water is life. We know it's essential to us. Our bodies are 60% h, two o and those of all organisms on earth, from the smallest bacteria to the largest elephants, Wales, aspen trees, and sequoia. In Norway, where I'm lucky enough to be speaking today, it's easy to take water for granted because we're blessed with abundant rainfall and majestic fjords. But even here, where water seems abundant, its significance cannot be overstated.

Norway's hydroelectric prowess is globally renowned powering industries and homes alike, while its famous waterfalls and fjords sustain thriving ecosystems, water is also the cornerstone of our agricultural systems. Even if challenges associated with growing populations and resource scarcity call this into question. Through irrigation and aquaculture, water so far sustains our food production. All this we know. I'm recapping familiar territory. Water is so normal, so everyday, that we consider it ordinary, not extraordinary. So what makes ice, liquid water and water vapor worthy of a rethink? We'll take a journey through the phases to find out.

Let's start with the solid form. Now, pretty much every solid in our universe is more dense than its liquid form. Think about gold or iron. They would sink if placed in a bath of the same material. This makes sense. We presume, using kinetic theory, the idea that solids are composed of particles close together and vibrating, whereas particles in a liquid are able to flow to fill the base of their container, having weaker forces in the. But the density of solids, that's the mass they contain in a given volume, is greater than liquids. But ice solid water isn't like this. It floats. We know this from fast food restaurants and cold drinks. On summer days, frozen water ice floats. But you might not know what sets ice apart from nearly all other solids. Its unique molecular structure.

At the molecular level, water molecules arrange themselves into a hexagonal lattice when they freeze, due to attractive so called hydrogen bonds between the unevenly distributed electric charges in the h two o molecules. When water freezes, its molecules form an open framework, with each molecule bonded to four others in an arrangement containing empty space. Unlike solid hydrogen, which is more dense than liquid hydrogen, and solid oxygen, which is more dense than liquid oxygen, solid water is less dense than than liquid water. And here's the magic the importance of these forces and densities to our lives, as well as being the only familiar substance to exhibit this property. If ice were denser than liquid water, it would sink. Lakes and rivers could freeze from the bottom up, threatening aquatic life with each drop in temperature.

Because ice floats, it forms an insulating layer on the surface, allowing life to thrive beneath it, even in the coldest of winters. This property of ice has profound implications for our planet. It's not just the picturesque beauty of snow capped mountains or the joy of skating on a frozen pond. It's about the stability of ecosystems, the regulation of climate and the very essence of life itself. So the next time you marvel at a glass of ice water or watch snowflakes gently blanket the earth, take a moment to appreciate the remarkable physics at play. The simple fact that ice floats begins to reveal the wonders of the universe that become visible when we remember to wear our physics glasses.

This can only mean one thing. It's time for us to plunge into the next discussion on liquid water. When was the last time you paused to consider the kaleidoscope of colours that water can exhibit, from the serene blue of lagoons to the vibrant hues of a rainbow reflected in a raindroplet? I have a hunch that water is one of the things that children consider to be most colorful in our world. And yet school teaches us that water is transparent, invisible. So what exactly gives rise to this astonishing diversity of colours?

We'll begin by exploring why rivers appear brown, even though the water itself is nothing. As water flows through riverbeds, it carries suspended particles, such as soil, silt, and organic matter. These particles scatter light in myriad directions, giving the water a brownish tint. The more suspended particles present, the darker the water appears, akin to looking through a cloudy window. The scattered light dims the clarity. It's what's present with the water that defines what we see now.

Consider the breathtaking blues of oceans. In this case, what gives water its ability to exhibit these extraordinary colors is, as with earlier, its molecular structure warriors. Iconic blue is a result of a phenomenon known as selective absorption. Water molecules, with their two hydrogen atoms and one oxygen atom, selectively absorb longer wavelengths. That's the distance between successive wave breadths of light waves, such as reds and oranges, while allowing shorter wavelengths like blues and greens to transmit. As sunlight penetrates water of vast quantities, these shorter wavelengths dominate in the light that reaches the cone cells for color at the backs of our eyes.

And what about rainbows, the ultimate in water creating color? The answer lies in how water affects light. When sunlight encounters a water droplet, it undergoes refraction that's changing direction as it enters and exits the droplet. The different colours of light correspond to different wavelengths, and each wavelength has a different refractive index, the ratio of the speed of light entering to the speed of light inside a material. This continuous spectrum of speeds links to a continuous spectrum of directions of light inside the water droplet, which means that the light that appeared white on entry reveals the perfect rainbow of red, orange, yellow, green, blue, indigo and violet wavelengths within the same effect that we see in this prism, made famous by this Pink Floyd album cover.

Furthermore, as the dispersed light comes to exit the droplet, some undergoes reflection within the droplet, further enhancing the brilliance of the rainbow, akin to the sparkles that we perceive when looking at a diamond. Because, like a diamond, the water droplet has a higher optical density than the air that surrounds it. In short, to me, what makes liquid water so special is its ability to unlock and set free the colors of light. And I could go on.

Water is half of the cause of the spectacular iridescence observable on a peacock feather or in oily puddles, caused by the interference of incident and reflected light waves within a thin film. Mike Lee the next time you gaze upon a body of water, take a moment to appreciate the physics at play, the light that your eyes are receiving and the emotions you experience as a result.

So now that we've sealed our liquid section, let's travel upwards and outwards to the third and final phase of vapor. To me, this is the least expected element in this exercise of rethinking I could have talked about water vapor, as found in power station boilers, idyllic steam train journeys, or clothing manufacturers. Or I could have indulged you, as I do my classes, in a discussion about the differences between boiling and evaporation and the relationship between thermal energy and temperature.

But I've chosen a focus that might just surprise you, because it's not something we often associate with h two o the greenhouse effect when we think of greenhouse gases, what comes to mind? My guess is carbon dioxide, methane or nitrous oxide. But what if I told you there's another greenhouse gas, one that rarely gets the attention it deserves? That's right, it's water vapor. It's often overlooked in discussions about climate change. Yet water vapor plays a significant role in shaping our planet's climate.

Firstly, of all the things found in our atmosphere, let's discuss what makes a substance a greenhouse gas. Unlike other substances, greenhouse gases resonate like a mass connected to a spring in the presence of infrared radiation. Infrared radiation is the region of the electromagnetic spectrum that we experience through through our skin as heat. Unlike radio waves, microwaves, visible light, ultraviolet radiation, x rays and gamma radiation, which our bodies and man made sensors detect in other ways. Greyhouse gases absorb infrared radiation like a spring absorbs energy, which means heat leaving the surface of the earth doesn't make it out through the atmosphere.

I then liken them to this speaker, which emits sound in all directions, up, down, left and right. It's the infrared radiation that's emitted back down, sometimes loosely referred to as trapped heat, that has an upward effect on global temperatures. And of course, the higher the concentrations of greenhouse gases, the more infrared departing the warm earth that is absorbed, emitted and returned to us. This greenhouse effect leads to global warming. And water vapor, despite being a fundamental component of our atmosphere, operates on the same principle. Water vapor, like carbon dioxide, is incredibly efficient at absorbing infrared radiation emitted by the earth's surface.

Water vapor, like carbon dioxide, amplifies the greenhouse effect, contributing to the increasing temperatures of our planet. What sets water vapor apart from other greenhouse gases is both its abundance and variability. Unlike carbon dioxide or methane, which have relatively stable concentrations in the atmosphere, on the long term, water vapour levels can fluctuate dramatically based on factors such as temperature, humidity and weather patterns. These fluctuations can amplify or dampen the greenhouse effect, leading to complex feedback mechanisms that influence our climate in profound ways. Think about it.

These intricate feedback loops that influence rates of climate change mean that as the Earth warms due to increased greenhouse gas emissions, more ice melts at the poles, and more liquid water evaporates into the atmosphere, further intensifying the greenhouse effect. So why don't we hear more about water vapor's role in climate change? Perhaps because water vapor is so integral to our daily lives, its significance goes unnoticed. Yet as we confront the realities of a changing climate, it's essential that we recognize the pivotal role that water vapor plays in shaping our planet's climate system.

By understanding and acknowledging the role of water vaporization, we can take meaningful steps towards building a more sustainable future for generations to come. And so here we are at the end of our journey through the phases of water. From the unexpected peculiarity of solid water floating on its liquid form, to the colors associated with rivers, oceans and rainbows, to less familiar greenhouse gases. I hope that you share my belief that water is, in and of itself, interesting. If I may make an even bigger splash, I might go so far as to say that the number of molecules known to our chemist friends is in the tens of millions, and suggest that these two might be just as worthy of diving into exercises in rethinking through the lens of physics provide insights into the largest and smallest bodies in the universe and everything in between.

Science, Education, Global, Water, Physics, Environmental Impact, Tedx Talks