Atmosphere and Atmospheric Layers Vocabulary

Flashcards for reviewing key atmospheric definitions, layer boundaries, radiation units, and composition standards.

Atmosphere Composition

The primary gaseous components of dry air by volume: Nitrogen ($\text{N}_2$) at $78.08\%$ and Oxygen ($\text{O}_2$) at $20.95\%$.

Nautical Mile (nm)

A navigational unit of distance defined as $6080\,\text{ft}$ or $1.852\,\text{km}$.

Temperature Lapse Rate Profiles

The vertical structure of temperature changes in the atmosphere, categorized into surface inversions, normal lapse rates, inversions aloft, and isothermal layers.

Tropopause

The atmospheric boundary between the troposphere and stratosphere where temperature stops decreasing with height and remains constant.

Tropopause Latitudinal Heights

The variation in tropopause height across latitudes, measuring $25{,}000\,\text{ft}$ at the poles (Polar TP) and $55{,}000\,\text{ft}$ at the equator (Tropical TP).

Sea-Level Ozone Equivalent Thickness

The compressed thickness of all atmospheric ozone if brought to sea level under standard temperature and pressure conditions, equal to $3\,\text{mm}$.

Dosimeter

A radiation detection device required onboard aircraft operating above $15\,\text{km}$ ($49{,}000\,\text{ft}$) to monitor exposure to cosmic radiation.

Stratopause

The upper boundary of the stratosphere at approximately $50\,\text{km}$ altitude, where temperature reaches about $0\,^\circ\text{C}$ due to UV absorption by ozone.

Mesopause

The boundary at the top of the mesosphere at approximately $80\,\text{km}$ altitude, where the lowest non-ISA atmospheric temperature of approximately $-90\,^\circ\text{C}$ occurs.

Ionosphere

A region within the thermosphere extending up to about $700\,\text{km}$ that contains free electrons, allowing the propagation of radio waves.