That’s a much more useful way to understand the warning.
Why the Bottle’s Shape Matters
Not every water bottle is shaped the same way.
Some bottles are relatively straight-sided.
Others have pronounced curves around the middle, bottom, or neck.
Those curves can influence how light passes through the bottle.
A transparent container that happens to create a focusing effect is more relevant to this concern than a bottle whose shape simply allows sunlight to pass through without concentrating it significantly.
This is one reason you shouldn’t assume every bottle presents exactly the same risk.
Why the Position of the Bottle Matters
This may be the most important part.
That’s a much more useful way to understand the warning.
Why the Bottle’s Shape Matters
Not every water bottle is shaped the same way.
Some bottles are relatively straight-sided.
Others have pronounced curves around the middle, bottom, or neck.
Those curves can influence how light passes through the bottle.
A transparent container that happens to create a focusing effect is more relevant to this concern than a bottle whose shape simply allows sunlight to pass through without concentrating it significantly.
This is one reason you shouldn’t assume every bottle presents exactly the same risk.
Why the Position of the Bottle Matters
This may be the most important part.
