While it should be a prevalent topic in science education that everyone gets told at one point or another, I can't say I'm surprised that people get it wrong. For most people it's just a fact to file away, and they don't really grasp it (a failing of the education system).
But it's got to do with everyday experience and that pesky "common sense" that often does more harm than good in science. People intuitively know that proximity to a heat source means it's hotter, but few have internalized
why it's hotter. As such they don't understand that by changing the way one is facing the heat source can also change the temperature, for the exact same reasons that getting closer makes it hotter.
Since people don't incorporate flux (the concept in question here, defined as the flow of something, like light, through an area) they don't have anything to tie that fact into after they've learned it. And so it gets lost. Unfortunately, for most people even if they learn about flux, it has so little role in their daily lives that they lose that too.
For anybody reading this, and who doesn't already understand why it's warmer in the summer I'll explain. It's based on the concept of Flux, which is the flow of something through an area. Now this can be anything, water, light, energy, magnetic fields, electricity, you name it.
Now, to use the concept you have to identify the source, in our example the sun, and what's flowing which is light this time. You then have to draw the flow lines, or how the substance is leaving the source. In our case it's a simple case of drawing lines straight out from the sun, radially in all directions (think happy kindergarten suns!). Sometimes it's more complicated than that, it may be like the magnetic (or electric) field lines about the earth or a magnet, which go out from one pole, and in at another.
Next you identify the area you're investigating, and observe how many of these "lines" pass through the area. That's it, thats flux
.
The complicated part comes in observing how it changes depending on what you do with the area. Take it closer to the sun, and it's going to intercept more lines...which means it's getting more light, and transfering more energy (making it hotter in this case). But you can ALSO just change how the area is facing, and turn it sideways. As you do so, that area (which is very thin) will intercept less lines...and become cool, exactly as if you'd moved it further away.
There's two little experiments you can do real quick to get a feel for how this works if you'd like. One is simply play with a flashlight. Find a small piece of paper, and shine the light straight down it, and look at how bright the reflection is, ONLY on the paper. Now bring the flashlight closer and take another look, then further away. You'll notice that as you bring it closer, it gets brighter, and further is dimmer. For the next step put the flashlight back where you started, but then move it off to shine at an angle while keep it the same distance from the paper. You'll notice that the paper now reflects less light, as most of it is 'wasted' on the rest of the table.
For a more tangible grasp of how the angle of a surface affects flux, just drag a knife, spoon, spatula or some flat surfaced item through water. Without changing speed you can easily feel how the resistance changes depending on if you hold the utensil flat on to the water, or edge on as you move it. This is also due to the flux of water that impacts the surface. Flat on is higher flux, meaning more resistance, edge on is less flux, and less resistance.
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