Quote Originally Posted by dr. d View Post
so they can do the measurements on nice, sunny days only?
kapag ma-ulap or na-ulan, hindi puede?
Still possible, but not as accurate. Calibration would be difficult. The instrument relies on the principle of absorption of UV light w/c is proportional to the amount of SO2. Thicker "steam", more absorption. As shown in the above diagram, the instrument will have a hard time to distinguish w/c are clouds and w/c is the steam coming from the volcano. It would give a reading but anomalously and unacceptably high.