Juno will improve our understanding of our solar system's beginnings by revealing the origin and evolution of Jupiter. Among other things, Juno will examine Jupiter's atmosphere to determine how deep the Great Red Spot and other atmospheric features reach, how much water is present, and its composition, temperature and cloud motions.
In orbit about this hottest planet, the Venus Express is digging into the secrets of its atmosphere. Venus Express is the first satellite able to study the atmosphere below the cloud tops, by using near-infrared "spectral window" wavelengths.
Cassini is currently in an extended mission called the Cassini Solstice Mission, named for the Saturnian summer solstice occurring in May 2017. Since Cassini arrived at Saturn just after the planet's northern winter solstice, the extension will allow for the first study of a complete seasonal period studying the weather of this gas giant and the weather on its moon Titan, among many other mission objectives.
NASA Earth Observing Missions: Earth's Atmosphere
There are a variety of satellites in orbit around our own world, studying out atmospheric composition, weather and climate, as well as other Earth systems.