humidity tray

[RosieC]

I think Naoki and Ray have 'hit the nail on the head'.

Humid air drops, so you are filling up your room, before you fill up the area above the tray. It basically has to raise the humidity of the whole room.

If you have sides up past the orchid (for example a tank with them in) them water in the bottom will raise humidity inside, but if there are no sides it will just fall away.