Editing Contour line (section)

==== Rainfall and air moisture ====
An '''isohyet''' or '''isohyetal line''' ({{ety|grc|''ὑετός'' (huetos)|rain}}) is a line on a [[map]] joining points of equal rainfall in a given period. A map with isohyets is called an '''isohyetal map'''.

An '''isohume''' is a line of constant relative [[humidity]], while an '''isodrosotherm''' ({{ety|grc|''δρόσος'' (drosos)|dew||''θέρμη'' (therme)|heat}}) is a line of equal or constant [[dew point]].

An '''isoneph''' is a line indicating equal [[cloud]] cover.

An '''isochalaz''' is a line of constant frequency of [[hail]] storms, and an '''isobront''' is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously.

[[Snow]] cover is frequently shown as a contour-line map.