AOSC 400 Unit 1: Atmospheric Structure and Measurement

Vocabulary flashcards covering the vertical layers of Earth's atmosphere, state variable measurement tools, and ground-based and airborne meteorological networks.

Troposphere

The lowest layer of Earth's atmosphere, extending from the surface to roughly $16\text{--}20\,\text{km}$ in the tropics, $10\text{--}12\,\text{km}$ at mid-latitudes, and $7\,\text{km}$ over winter poles; contains about $75\%$ of atmospheric mass, $99\%$ of water vapor, and most aerosols.

Tropopause

The boundary layer marking the top of the troposphere where the thermal lapse rate falls to $2\,\text{K}\,\text{km}^{-1}$ or less, creating strong static stability that suppresses convective thunderstorm growth.

Stratosphere

The layer extending from the tropopause to approximately $50\,\text{km}$, where temperature increases with height due to ultraviolet radiation absorption by the ozone layer.

Stratopause

The transition boundary located near $50\,\text{km}$ altitude between the stratosphere and mesosphere where temperature stops increasing with altitude.

Mesosphere

The atmospheric layer extending from $50\,\text{km}$ to $85\,\text{km}$ where temperature drops with altitude to atmospheric minimums of approximately $-90\,^{\circ}\text{C}$ and most meteoroids burn up.

Mesopause

The boundary layer located at approximately $85\,\text{km}$ altitude separating the mesosphere from the thermosphere, where temperature stops decreasing with height.

Thermosphere

The layer located between $85\,\text{km}$ and $500\text{--}1,000\,\text{km}$ altitude that absorbs high-energy solar X-rays and UV radiation, driving temperatures to hundreds or thousands of degrees Celsius.

Kármán Line

The approximate boundary between Earth's atmosphere and outer space, located within the thermosphere at an altitude of roughly $100\,\text{km}$.

Ionosphere

Overlapping regions within the mesosphere and thermosphere where energetic solar radiation knocks electrons off air molecules, creating electrically charged ions.

Thermopause

The transition boundary between the thermosphere and exosphere where temperature remains constant with height.

Exosphere

The outermost atmospheric layer fading into space between $100,000\,\text{km}$ and $190,000\,\text{km}$, where extremely low air density causes gas particles to follow ballistic trajectories without frequent collisions.

Magnetosphere

A region surrounding Earth created by an active interior dynamo, in which charged particles are governed by Earth's magnetic field.

Plasmasphere

A region located inside Earth's magnetosphere that consists of low-energy (cool) plasma containing charged ions and electrons.

Sling Psychrometer

A type of hygrometer comprising a dry-bulb thermometer and a wet-bulb thermometer that is whirled in the air to derive relative humidity via evaporative cooling.

Barometer

An instrument designed to measure atmospheric force per unit area (air pressure), such as a mercury column evacuation tube balance.

Anemometer

An instrument used to measure wind speed, or both wind speed and wind direction when designed as a windmill anemometer.

Weather Vane

An instrument that indicates wind direction, defined as the direction from which the wind is blowing.

Rain Gauge

A cylindrical measuring instrument with an attached funnel lid used to collect and record liquid precipitation depth over a specific surface area.

Snowboard

A flat board placed on the ground used to measure newly accumulated snowfall depth to the nearest tenth of an inch up to four times in a 24-hour period.

Snow Water Equivalent

The total depth of liquid water obtained when a core sample of snowpack is melted, used primarily to evaluate river flooding potential.

Snow Ratio

The proportion of accumulated snow depth relative to its liquid water content (historically estimated at $10:1$), influenced by cloud ice content, temperature profiles, and wind speed.

ASOS (Automated Surface Observing System)

A primary surface weather observation network operated by NOAA NWS, FAA, and DOD across more than 900 locations delivering automated continuous observations every minute.

AWOS (Automated Weather Observing System)

An automated surface weather station network managed by the Federal Aviation Administration (FAA) that transmits weather reporting data every minute.

USCRN (U.S. Climate Reference Network)

A network of over 120 standardized stations across the U.S. providing high-quality, long-term air temperature and precipitation monitoring with minimal time-dependent bias.

Mesonet

A network of automated environmental monitoring stations spaced to observe weather events across mesoscale spatial dimensions ($1\text{--}150\,\text{miles}$).

Micronet

A high-density surface observation network with smaller station spacing than a mesonet, tailored to monitor localized urban or metropolitan weather conditions.

Radiosonde

An instrument package launched on a weather balloon to gather vertical profiles of temperature, atmospheric pressure, relative humidity, and wind vector data.

Rawinsonde

A radiosonde explicitly tracked with navigation technology to allow calculation of wind speed and wind direction at various vertical levels.

Dropsonde

An instrument package dropped via parachute from aircraft to measure vertical profile parameters (temperature, pressure, humidity, wind) as it falls through storm systems.

AMDAR (Aircraft Meteorological Data Relay)

An international program collecting and transmitting automated atmospheric observations recorded by sensors on commercial and research aircraft.