Weather balloons, as well as specially prepared aircrafts, are used to retrieve several atmosphere parameters at different altitudes that are latter used to feed mathematical models for weather prediction.
Nowadays airliners are already fitted with multiples sensors (static pressure, temperature, weather radar,..). Those airliners are flying almost all over the world continuously, and are thus able to provide tons of weather data. In many regions (inside TMA and above) data can be retrieve from ground level to 12000m above mean sea level. Those data won't be as complete as data collected by weather balloons, but can be considered as additional data. Yet, airliners are operated by private company and exchanging such data can be subjected to commercial contracts.
Are airliners, whose primary mission is not to collect weather data but to transport cargo or passengers, used to retrieve additional data to feed mathematical weather prediction models on a daily basis?