Trace gas Trace gas The most abundant gases in the atmosphere are nitrogen (78.1%), oxygen (20.9%), and argon (0.934%). Combined, oxygen, argon, and nitrogen make up 99.934% of the gases in the atmosphere (not including water vapor). The other gases that are not part of the 99.934% of the atmosphere are called trace gases. The abundance of a trace gas can range from a few parts per trillion (ppt) by volume to several hundred parts per million by volume (ppmv). When a trace gas is added into the atmosphere, that process is called a "source". There are two possible types of sources
Most common words in Spanish of spoken Spanish. Most common words in Spanish Below are two estimates of the most common words in Modern Spanish. Each estimate comes from an analysis of a different text corpus. A "text corpus" is a large collection of samples of written and/or spoken language, that has been carefully prepared for linguistic analysis. To determine which words are the most common, researchers create a database of all the words found in the corpus, and categorise them based on the context in which they are used. The first table lists the 100 most common word forms from the Corpus de Referencia