When we go to the beach, it’s rarely to rack our brains with bullshit questions, the answers to which are anything but obvious. That’s good, I’m not going to the beach. So I have the right to rack my brains, with bullshit questions, in order to make their answers obvious. Why is sea water salty?
1. Why is the water salty?
You have to go back a long (very long) time to understand. 4 billion years ago, our blue planet was covered in volcanoes that released water vapor and gases (including chlorine and sulfur) into the atmosphere. When the oceans formed a few hundred million years later, they absorbed these gases, which then dissolved into sulphate, which began to salt the water. During the millions of years that followed, the phenomenon was reinforced by soil erosion. Indeed, the rain, streaming on the rocks before ending up in the water, continued (and continues) to bring different minerals involved in the salinity of the water such as sodium, calcium, potassium and magnesium.
2. How many grams of salt are there in the water?
There are approximately 34.7 g of salt for one liter of water. All oceans combined, this is equivalent to 49 million billion tons of salt. If you’re wondering, it’s written 49,000,000,000,000,000 (15 zeros), in numbers. It’s a lot. Very much.
3. How many grains of sand are there on Earth?
Rest assured, no one has tried the experiment of counting them one by one. Clearly, it’s something to finish completely maboul after 20 meters. However, little geniuses lent themselves to the horrible game of mathematics, and made hypotheses based on obscure calculations that I do not understand at all. According to Howard C. McAllister, professor of physics at the University of Hawaii, there are 7.5 trillion (7,500,000,000,000,000,000 grains of sand). For his part, Eric Chaumillon, a researcher at the University of La Rochelle (it’s less dreamy than Hawaii), estimated their number at 200 million billion billion (2 x 10 to the power of 26). Well, finally… We’re not much further ahead, huh. (Source)
4. Besides, why is there sand at the bottom of the water?
Once again, everything is linked to erosion! The ocean water wets the rocks, which weaken and break into pebbles. These pebbles are carried away by the waves which break them again. One thing leading to another, the small pieces of broken and re-cracked rocks form the sand. The latter ends up at the bottom of the water, then is washed up on the beach. CQFD. Other questions ? Yes ? We continue.
5. Why are pebbles sometimes used instead?
The composition of the beaches (more or less fine sand or pebbles) depends above all on the geological formation of the region. As we explained for the sand: the beaches are essentially the result of the erosion of the surrounding rocks. In Normandy, for example, the rocks are mostly made of chalk enclosing flint pebbles. When chalk is eroded by rain, wind or the sea itself, it releases pebbles. And TADAAAAAM, that’s pebble beaches that really hurt your feet. (Source)
6. Why are there tides?
These water movements are caused by… The Moon. Yes yes. This natural satellite of the Earth attracts towards it these expanses of fleet with each of its passages. If the Sun aligns with the Moon, the phenomenon is further reinforced and causes what are called “high tides” or “spring tides”. As the Earth rotates on itself in 24 hours, the oceans are not always facing the Moon. As it moves away from the star, the attraction decreases and the ocean returns to its starting position: the tide rises.
Contrary to what we tend to believe, the tides are not reserved for the oceans: they also exist for the seas. They are just less noticeable, because the stretch of water is much lower, and atmospheric conditions such as headwinds mitigate the phenomenon.
7. How do waves form?
The waves result from the meeting of two elements: water and air, far from the shore, in the open sea. On the waters can form a low pressure system (a low pressure regime) which can bring bad weather. When it meets its opposite (the anticyclones), the wind blows between the two to balance atmospheric pressure. In this way, the wind creates a wave, which then becomes a wave. (Source)
8. Why is the sea blue?
The light that the sun diffuses on Earth is white: it is composed of all the colors of the rainbow, with different wavelengths, covering the spectrum from infrared to ultraviolet. Upon encountering water, light decomposes. The red side of the light spectrum is absorbed, while the blue side is reflected. In this way, our eyes perceive green and blue radiation. The greater the number of “absorbent” molecules, the more this color is marked. This is why, in a thin thickness like a glass of water, the water appears transparent, whereas where the depth is significant, it comes out navy blue and opaque.
9. And why is it clearer sometimes?
Several factors come into play: depth, first. The deeper the sea, the less light is reflected and the darker it appears to us. However, in some lagoons, even offshore, the water remains very clear, even turquoise. In fact, it is because the color of the bottom also influences the appearance of the water. Very light sand will give a clearer appearance to the sea. Finally, organic production also has a role to play. Where there are phytoplankton, there is chlorophyll. This absorbs the blue component and helps the light to shift towards the green. (Source)
10. Why do people tan better at the sea than in the swimming pool?
Because water and salt favor the reverberation of the sun. Indeed, the salt contained in the water reflects sunlight better and thus constitutes a natural tanning accelerator. We will take this opportunity to note that UV rays penetrate water up to 30 cm deep, and that it reflects between 10% and 30% of the sun’s rays.
11. Bonus: why is there always an asshole to stick his napkin to yours?