Which type of clouds appear at lower altitudes, look dark and dense and bring plenty of rain?
With reference to Clouds, consider the following statements: 1. Cirrus clouds are formed at low altitudes. 2. Stratus clouds are layered clouds. 3. Nimbus Clouds are extremely dense and opaque to rays of sun. 4. Cumulus clouds exist in patches and can be seen scattered. Which of the above statement(s) is/are correct?