(käm pau̇nd): A distinct substance formed by the union of two or more chemical elements in definite proportion by weight.

(dǝkt): A pipe, tube, or channel through which a substance (like air or water) flows.

(ē kō sis tǝm): A system made up of an ecological community of living things interacting with their environment especially under natural conditions.

(ē mi shǝn): Something emitted or discharged, usually into the air.

(ga sē ǝs or ga shǝs): Having the form of or being gas.

(mä li kyül): The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.

(plüm): Something resembling a feather, such as an elongated and usually open and mobile column or band (for example: of smoke, exhaust gases, or blowing snow).

(sam pəl): A small subset group, representative of the entire group.

(sim yǝ lāt): To make an imitation (or copy or model) by one system or process of the way in which another system or process works.

(trō pǝ sfir): The portion of the atmosphere which extends from the Earth’s surface to the bottom of the stratosphere (a distance of about 7 miles or 11 kilometers) and in which temperature generally decreases rapidly with altitude.

(ǝp wind): In the direction from which the wind is blowing.

(ve jǝ tā shǝn): Plant life or total plant cover of an area.