Week 18 Vocab

Precipitation, such as rain, sleet, or snow, that contains a high concentration of acids, often because of the pollution of the atmosphere.

A value that is used to express the acidity or alkalinity (basicity) of a system; each whole number on the scale indicates a tenfold change in acidity; a pH of 7 is neutral, a pH of less than 7 is acidic, and a pH of greater than 7 is basic.

The sudden runoff of large amounts of highly acidic water into lakes and streams when snow melts in the spring or when heavy rains follow a drought.

The average weather conditions in an area over a long period of time.

The distance north or south from the equator; expressed in degrees.

The warm phase of the El Nino-Southern Oscillation; a periodic occurrence in the eastern Pacific Ocean in which the surface-water temperature becomes unusually warm.

The cool phase of the El Nino-Southern Oscillation; a periodic occurrence in the Eastern Pacific Ocean in which the surface-water temperature becomes unusually cool.

The layer of the atmosphere at an altitude of 15 to 40 km in which the ozone absorbs ultraviolet solar radiation.

Hydrocarbons in which some or all of the hydrogen atoms are replaced by chlorine and fluorine; used in coolants for refrigerators and air conditioners and in cleaning solvents; their use is restricted because they destroy ozone molecules in the stratosphere.

A thinning of stratospheric ozone that occurs over the poles during the spring.

A cloud that forms at altitudes of about 21,000 m during the Arctic and Antarctic winter or early spring, when air temperatures drop below -80C

A gas composed of molecules that absorb and radiate infrared radiation from the sun.

A gradual increase in average global temperature.

An international treaty according to which developed countries that signed the treaty agree to reduce their emissions of carbon dioxide and other gases that may contribute to global warming by 2012.