In Śāntiparva (Santiparva) of Mahābhārata (Mahabharata), it is said that the airy sphere above the ground-level, where moisture from water is created by the help of sun-rays, is called ‘Pravaha’.
The next sphere, whereto the clouds filled with moisture are transported from ‘Pravaha’, is called Āvaha (Avaha). Its modern name is Troposphere. In Mahābhārata (Mahabharata), this ‘Troposphere’ is said to be divided in two areas.

In Matsya, Vāyu(Vayu) and Brahmāṇdapurāṇa (Brahmandapurana), Āvaha is said to be the first level of atmosphere.

However, in Skandapurāṇa (Skandapurana), Āvaha is mentioned as the second sphere of the atmosphere.