The grating, crackling or popping sounds and sensations experienced under the skin and joints when two rough surfaces in the human body come into contact; sound and senseation produced in soft tissues when gas is introduced into an area where it normally isn't present; the crackling wheezing sounds produced by lung conditions; the noise produced by a sudden discharge of wind from the bowels.
The common rain smell is a gas called petrichor. Volatiles evaporate from plants and are absorbed by rocks, concrete etc. When the rain hits the rock, the volatiles are released into the atmosphere and you smell it.
A freshwater aquifer below a tropical ocean island; rainwater percolates through the island and floats above the surrounding seawater; this groundwater forms a root shape beneath the island, usually 40 times as thick as below sea level as above.
(noun) 1. A sheet of water flowing over a dam or similar structure. 2. (Geology) A large sheetlike body of rock that has been moved far from its original position. 3. (Mathematics) Either of the two parts into which a cone is divided by the vertex.