A fumarole (or fumerole – the word ultimately comes from the Latin fumus, "smoke") is an opening in a planet's crust which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, and hydrogen sulfide. The steam forms when superheated water boils as its pressure drops when it emerges from the ground. A fumarole that emits sulfurous gases can be referred to as a solfatara (from old Italian solfo, "sulfur", although the modern Italian spelling is zolfo). Fumaroles may occur along tiny cracks, along long fissure, or in chaotic clusters or fields. They also occur on the surface of lava or pyroclastic flows. A fumarole field is an area of thermal springs and gas vents where shallow magma or hot igneous rocks release gases or interact with groundwater. When they occur…
