A  cumulonimbus incus  (Latin  incus , "anvil") is a  cumulonimbus cloud  which has reached the level of  stratospheric stability  and has formed the characteristic flat,  anvil -top shape.  They can form into  supercells  resulting into severe storms like  tornadoes . More at: Wikipedia ___________________________________________  3. Lenticular Clouds Source:   Redditbot Are