| ISOLINES | DEFINITION |
| Isobar | A line representing points of equal atmospheric pressure |
| Isobaths | A line representing points of equal depth under water |
| Isobathytherm | A line representing depths of water with equal temperature |
| Isocheim | A line representing points of equal mean winter temperature |
| Isodose | A line representing points of equal intensity of radiation |
| Isodrosotherm | A line representing points of equal dew point |
| Isogeotherms | A line representing points of equal mean temperature |
| Isohaline | A line representing points of equal salinity in the ocean |
| Isohel | A line representing points receiving equal amounts of sunshine |
| Isohume | A line representing points of equal humidity |
| Isohyets | A line representing points of equal precipitation |
| Isoneph | A line representing points of equal amounts of cloud cover |
| Isophene | A line representing points where biological events occur at the same time, such as crops flowering |
| Isoplat | A line representing points of equal acidity, as in acid precipitation |
| Isopleths | A line representing points of equal numerical value, such as population |
| Isostere | A line representing points of equal atmospheric density |
| Isotac | A line representing points where ice begins to melt at the same time each spring |
| Isotach | A line representing points of equal wind speed |
| Isothere | A line representing points of equal mean summer temperature |
| Isotherm | A line representing points of equal temperature |