1.6% composed mostly of methane (1.4%) and hydrogen (0.1–0.2%). The main tholin haze layer lies in the stratosphere at about 100–210 km (62–130 mi). In this layer of the atmosphere there is a strong temperature inversion caused by the haze due to a high ratio of shortwave to infrared opacity. Mesosphere: A detached haze layer is found at about 450–500 km (280-310 mi), within the mesosphere. The temperature at this layer is similar to that of the thermosphere because of the cooling of hydrogen cyanide (HCN) lines. Thermosphere: Particle production begins in the thermosphere This was concluded after finding and measuring heavy ions and particles. This was also Cassini's closest approach in Titan's atmosphere. Ionosphere: Titan's ionosphere is also more complex than Earth's, with the main ionosphere at an altitude of 1,200 km (750 mi) but with an additional layer of charged particles at 63 km (39 mi). This splits Titan's atmosphere to some extent into two separate radio-resonating chambers. The source of natural extremely-low-frequency (ELF) waves on Titan, as detected by Cassini–Huygens, is unclear as there does not appear to be lightning activity. The main sources of Titan's ionosphere are solar irradiance, Saturn's magnetospheric electrons and ions (, , ), drifting along the magnetic field lines, and galactic cosmic rays (see more in ). Atmospheric composition and chemistry Titan's atmospheric chemistry is diverse and complex. Each layer of the atmosphere has unique chemical interactions occurring within that are then interacting with other sub layers in the atmosphere. For instance, the hydrocarbons are thought to form in Titan's upper atmosphere in reactions resulting from the breakup of methane by the Sun's ultraviolet light, producing a thick orange smog. The table below highlights the production and loss mechanisms of the most abundant photochemically produced molecules in Titan's atmosphere. Magnetic field Titan's internal magnetic field is negligible, and perhaps even nonexistent, although studies in 2008 showed that Titan retains remnants of Saturn's magnetic field on the brief occasions when it passes outside Saturn's magnetosphere and is directly exposed to the solar wind. This may ionize and carry away some molecules from the top of the atmosphere. One interesting case was detected as an example of the coronal mass ejection impact onto Saturn's magnetosphere, causing Titan's orbit to be exposed to the shocked solar wind in the magnetosheath. This leads to the increased particle precipitation and the formation of extreme electron densities in