HOPKINS GLOSSARY OF WEATHER TERMS M

maximum thermometer

• A thermometer designed to automatically register the highest temperature attained during any time interval before it is reset.

mesopause

• An extremely cold region of the earth's atmosphere (approximately -90°C) at an altitude of approximately 80 km, representing the boundary between the mesosphere and the overlying thermosphere.

mesosphere

• The region of the earth's atmosphere between the stratopause at the top of stratosphere (at an altitude of approximately 50 km) and mesopause, just below the thermosphere (70 to 80 km altitude) where the temperature decreases rapidly with height.

meteorograph

• A collection of automatic meteorological recording instruments, often times describing the package that is carried aloft on an instrument platform, such as a balloon or kite.

meteorological rocket (metrocket)

• A rocket containing a payload or either an instrument package (rocketsonde) or a radar-reflective falling sphere sent aloft to make routine upper atmospheric observations up to a 250,000 ft (76 km) altitude.

metrocket

• Contraction for meteorological rocket.

minimum thermometer

• A thermometer designed to automatically register the lowest temperature attained during any time interval before it is set.

mixing ratio

• A humidity measure, defined as the dimensionless ratio of the mass of water vapor to the mass of dry air. The mixing ratio is usually expressed in units of grams of water vapor to kilogram of dry air.

Mhz

• Abbreviation for mega Hertz, or a frequency of one million cycles per second.