Venetian Violet in the sun
11-22-2005, 03:24 PM
#14
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Are you an idiot?
You've obviously never studied optics, but you sure like to talk like you have.
The fact that you can see a tree on his hood simply means that to a first approximation the line of sight from his camera to his hood is at an angle with the hood which is identical to the angle off the hood in the opposite direction which leads to the tree. This is absolutely NOT the same as the physical definition of shade, which requires that light be absorbed BETWEEN THE LIGHT SOURCE AND THE OBJECT, which is not happening here (if we ignore the fact that the atmosphere always absorbs some of the Sun's light).
Go take a physics class (yes, I have a degree in it) and get your head out of your ***.
The fact that you can see a tree on his hood simply means that to a first approximation the line of sight from his camera to his hood is at an angle with the hood which is identical to the angle off the hood in the opposite direction which leads to the tree. This is absolutely NOT the same as the physical definition of shade, which requires that light be absorbed BETWEEN THE LIGHT SOURCE AND THE OBJECT, which is not happening here (if we ignore the fact that the atmosphere always absorbs some of the Sun's light).
Go take a physics class (yes, I have a degree in it) and get your head out of your ***.
11-22-2005, 04:05 PM
#15
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There is light being blocked from that tree as well. Degree or not, there isn't direct light on tha
car because of that tree. It is shade, but slight. Why? Because sunlight doesn't only come from where you see that round yellow ball in teh sky directly onto the car. There is light coming from behind the tree as well.
Nothing I said above is incorrect in terms of reducing direct sunlight on the car. There are plenty of other pictures on the web, taken at the same time of day, yet you see that it has unobstructed access to sunlight.
Nothing I said above is incorrect in terms of reducing direct sunlight on the car. There are plenty of other pictures on the web, taken at the same time of day, yet you see that it has unobstructed access to sunlight.
11-22-2005, 04:37 PM
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Not necessarily...
I get what you're trying to say, but you're not even absolutely correct. Think about a different, but similar example...
What if instead of a tree being there, we put a very bright spotlight which is locally brighter than daylight? We would see the spotlight reflected in the hood of the car. Would you still try to claim this is shade? Would you try to claim that there is less light falling on the car due to the presence of this spotlight? Clearly you'd be wrong.
So the point you're trying to make, that a reflection necessarily reduces the amount of light falling on object, requires that the sum of the intensity of all visible frequencies of light coming off the reflected object be less than what would be there were it not for the presence of this object, which is absolutely not a foregone conclusion. The sky, which is presumably what we would see were there no tree there, is fairly intense during the day, but is not necessarily more intense than sunlit objects.
In the case of this tree, a lot of the reflected tree is in shadow itself, so chances are you're right that in this case the total number of photons striking the car is reduced by its presence, but you're still wrong to call it shade. The proper definition of shade requires that the light source be directly blocked, not that its reflection and refraction off other objects be blocked. Before you tell me I've got it wrong here, remember that the sky you'd like to see in place of that tree is in fact itself just an object which is reflecting and refracting the light, eventually directing some of it back to the car. The tree is really no different from the sky if you really think it about it. It's just another object which is bouncing some fraction of the photons striking it onto the car and eventually into the camera. It is not shade.
If you want to see a picture of the car with nothing reflected in it, ask for that. Let's not go on trying to redefine physics.
What if instead of a tree being there, we put a very bright spotlight which is locally brighter than daylight? We would see the spotlight reflected in the hood of the car. Would you still try to claim this is shade? Would you try to claim that there is less light falling on the car due to the presence of this spotlight? Clearly you'd be wrong.
So the point you're trying to make, that a reflection necessarily reduces the amount of light falling on object, requires that the sum of the intensity of all visible frequencies of light coming off the reflected object be less than what would be there were it not for the presence of this object, which is absolutely not a foregone conclusion. The sky, which is presumably what we would see were there no tree there, is fairly intense during the day, but is not necessarily more intense than sunlit objects.
In the case of this tree, a lot of the reflected tree is in shadow itself, so chances are you're right that in this case the total number of photons striking the car is reduced by its presence, but you're still wrong to call it shade. The proper definition of shade requires that the light source be directly blocked, not that its reflection and refraction off other objects be blocked. Before you tell me I've got it wrong here, remember that the sky you'd like to see in place of that tree is in fact itself just an object which is reflecting and refracting the light, eventually directing some of it back to the car. The tree is really no different from the sky if you really think it about it. It's just another object which is bouncing some fraction of the photons striking it onto the car and eventually into the camera. It is not shade.
If you want to see a picture of the car with nothing reflected in it, ask for that. Let's not go on trying to redefine physics.
