So how does UVB get through the glass surrounding a UVB bulb if it can't easily/at all get through windows, etc?
Tom said:I'm not sure about your question, but here are two related points:
1. Ever get a sunburn through the window on a long car trip? I have. How can you get a sunburn if the glass filters out all the UV?
2. How come the UV can't get to your tortoise if the bulb is more than 12 or 18" from your tortoise? UV light travels millions of miles from the sun, penetrates all the layers of the atmosphere, all the dust, smoke, smog, fog, etc... and is still powerful enough to make D3 in our tortoises skin. Its still so strong after that that it bounces into the shade. A tortoise in the shade outside still gets enough UV to get the job done. So how come the UV generated by a bulb can't travel a few extra inches? Does it just stop and hover there at 18"?