Meteorology Chapter One

Ionosphere

An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist.

Thermosphere

The atmospheric layer above the mesosphere (above about 85 km) where the temperature increases rapidly with height.

Mesosphere

The atmospheric layer between the stratosphere and the thermosphere. Located at an average elevation between 50 and 80 km above Earth’s surface.

Stratosphere

The layer of the atmosphere above the troposphere and below the mesosphere (between 10 km and 50 km), generally characterized by an increase in temperature with height.

Tropopause

The boundary between the troposphere and the stratosphere.

Troposphere

The layer of the atmosphere extending from Earth’s surface up to the tropopause (about 10 km above the ground).

Radiosonde

A balloon-borne instrument that measures and transmits pressure, temperature, and humidity to a ground-based receiving station.

Temperature Inversion

An increase in air temperature with height, often simply called an inversion.

Lapse Rate

The rate at which an atmospheric variable (usually temperature) decreases with height.

Air Pressure

The pressure exerted by the mass of air above a given point, usually expressed in millibars, inches of mercury, or in hectopascals.

Air Density

The ratio of the mas of a substance to the volume occupied by it. Air density is usually expressed as g/cm³ or kg/m³

Pollutants

Any gaseous, chemical, or organic matter that contaminates the atmosphere, soil, or water.

Aerosols

Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere form either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols.

Ozone

An almost colorless gaseous form of oxygen with an odor similar to weak chlorine. The highest natural concentration is found in the stratosphere where it is known as stratospheric ozone. It also forms in polluted air near the surface where it is the main ingredient of photochemical smog. Here it is called tropospheric ozone.

Carbon Dioxide

A colorless, odorless gas whose concentration is about 0.039 percent in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in Earth’s atmospheric greenhouse effect. Solid CO2 is dry ice.

Atmosphere

The envelope of gases that surround a planet and are held to it by the planet’s gravitational attraction. Earth’s atmosphere is mainly nitrogen and oxygen.

Weather

The condition of the atmosphere at any particular time and place.

Weather Elements

The elements of air temperature, air pressure, humidity, visibility, wind, precipitation, and clouds that determine the present state of the atmosphere; the weather.

Climate

The accumulation of daily and seasonal weather events over a long period of time.

Meteorology

The study of the atmosphere and its phenomena, as well as the interaction between it and Earth’s surface, oceans, and life in general.

Middle Latitudes

The region of the world typically described as being between 30 degrees and 50 degrees latitude.

Middle-Latitude Cyclonic Storm System

A cyclonic storm that most often forms along a front in middle and high latitudes. Also called a middle-latitude cyclonic storm, a depression, and a low. It is not a tropical storm or hurricane.

Hurricane

A tropical cyclone with sustained winds of at least 64 knots (74 mi/hour).

Thunderstorms

A convective storm (cumulonimbus cloud) with lightning and thunder. Thunderstorms can be composed of an ordinary cell, multicells, or a rapidly rotating supercell.

Tornadoes

An intense, rotating column of air that often protrudes from a cumuliform cloud in the shape of a funnel or a rope whose circulation is present on the ground.

Wind

Air in motion relative to Earth’s surface.

Wind Direction

The direction from which wind is blowing.

Wind Speed

The rate at which the air moves by a stationary object, usually measured in miles/hour, knots, kilometers/hour, or meters/second.

Front

The transition zone between two distinct air masses.

Outgassing

The release of gases dissolved in hot, molten rock.

Nitrogen

A colorless and odorless gas that occupies about 78 percent of dry air in the lower atmosphere.

Oxygen

A colorless and odorless gas that occupies about 21 percent of dry air in the lower atmosphere.

Water Vapor

Water in a vapor (gas) form. Also called moisture.