swimmers often notice that when they start to swim in a still body of water after a hot sunny day the surface water is warm but the deeper water is cold.
why this happens?explain.
(is it that the heat of the sun can only heat up the surface of the water?)
swimmers often feel colder when they get out of the water even if the temperature of the air and the water is the same.
why is this?and why is the effect more noticeable if there is a breeze?
please help!
OK, I have 2 examples that might help you to understand... about the warm surface/ cold under, think about the ocean... the first few inches or so is warm, but the deeper you get, the colder it gets. It's the same with a pool; It's because there is so much water that it's hard for the sun to heat it up quickly.
As for the other example: You know how when you're playing a sport, you sweat? Then that cool breeze comes in and you feel better? That's how it is with when you are wet. Because of the water being so cold under the surface, your body gets used to that temperature... so when you get out, you still feel cold... Does that make any sense?
Yes, that makes sense! Let me explain in more detail.
When swimmers start to swim in a still body of water after a hot sunny day, they often notice that the surface water is warm, but the deeper water is cold. This happens because water is a poor conductor of heat. When the sun shines on the water, it primarily heats the top layer near the surface. This layer of warm water acts as an insulating barrier, preventing the heat from transferring downwards.
Additionally, the wind and wave action on the surface of the water can also mix the warmer surface water with the cooler water below, creating a more uniform temperature throughout the water column. However, in still water, there is minimal mixing, and the warm water remains concentrated near the surface while the deeper water remains colder.
Now, let's move on to the second question. Swimmers often feel colder when they get out of the water, even if the temperature of the air and water is the same. This is due to a phenomenon called evaporative cooling. When you're in the water, your body heats the surrounding water. As the water evaporates from your skin, it takes away a significant amount of heat energy, making you feel cooler.
When you get out of the water, the evaporation process continues, but since there is no longer a constant source of heat from your body, the cooling effect becomes more noticeable. This is especially true if there is a breeze. The breeze speeds up the evaporation process, causing the water on your skin to evaporate more quickly. As a result, you lose heat at a faster rate, making you feel even colder.
In summary, the temperature difference between the surface and deeper water in a still body of water after a hot sunny day is due to poor heat conductivity of water and minimal mixing. Swimmers feel colder when they get out of the water because of evaporative cooling, and the effect is more noticeable in the presence of a breeze.