Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.
Impossible to give an exact figure, because it depends on the wavelength of the infrared beam and also on whether the air is dry or damp. It also depends on the barometric pressure. Unless you demand a high degree of accuracy, the refractive index will be the same as that of visible light, a tiny fraction above 1.
