A tornado often forms in an area where rain is not
falling, although rain can and does form in the area immediately around it,
often wrapping around the tornado on one side as a "rain curtain" that hides it from a
viewer. Storm spotters and chasers know that one of the most dangerous
situations to be in is one in which a rain curtain is between the observer
and a potential tornado because it hides the tornado from view. Fortunately,
the rain curtain usually forms after the funnel has touched down.