| Extensive isothermal layer, ice particles and water droplets must exist just below the freezing level and orographic lifting. |
| Environmental lapse rate less than saturated adiabatic lapse rate with dew point below 0 °C and considerable surface heating. |
| Environmental lapse rate greater than saturated adiabatic lapse rate through a great vertical extent, high relative humidity and an initial lifting process. |
| Environmental lapse rate less than dry adiabatic lapse rate with freezing level below the cloud base, high relative humidity and strong surface winds. |
EN 