What are the different types of hail, frost, rainstorm and dark clouds?

Dark clouds. Hail, frost and rainstorm are all directly related to weather phenomena, but dark clouds are not. Hail, frost and rainstorm are all solid precipitation in nature due to specific meteorological conditions, such as temperature, humidity and atmospheric flow, while dark clouds represent a state in the sky and are clouds formed by condensation of water vapor in the air, usually due to the increase of water vapor in the atmosphere or other meteorological conditions. Dark clouds can predict the occurrence of rainfall, snowfall or other weather phenomena, but they are not a weather phenomenon in themselves, so dark clouds are different among hail, frost, rainstorm and dark clouds.