In a sharp-core spherical micelle of aggregation number $n$, incompressible tail volume $v$ per molecule and effective head-group area $a_0$ give $nv=4\pi R^3/3$ and $n{a}_0=4\pi R^2$. Division gives the displayed radius and aggregation number. If the maximum tail extension is $l_c$, the model requires $R\le l_c$, equivalently the amphiphile packing parameter $v/(a_0{l}_c)\le 1/3$. Input dimensions violating that inequality cannot describe an exact spherical filled core without modifying the molecular geometry assumptions.

The number of constituent molecules in an aggregate. An observed population generally has a distribution of aggregation numbers.

For a long cylindrical micelle with negligible end caps, incompressible tail volume $v$ and head-group area $a_0$ give $v/a_0=R/2$. The geometric requirement $R\le {\ell }_c$ bounds the amphiphile packing parameter by $1/2$. The conventional cylindrical range is approximately $1/3\lesssim v/(a_0{\ell }_c)\lesssim 1/2$; aggregate transitions also depend on interactions and chain conformations.

A suspension of liquid-water droplets, ice particles or both in an atmosphere. Clouds interact with solar and thermal radiation; their net radiative effect depends on height, water content, particle size distribution and coverage.

An atmospheric electrical discharge. Its high-temperature chemistry can produce nitrogen oxides, influencing ozone and radical chemistry away from surface emission sources. The ozone response depends on subsequent transport and the local chemical regime.

Condensed water falling from clouds or deposited from the atmosphere as liquid or solid particles. It can efficiently scavenge soluble gases and aerosol particles. Gas conversion into sulfate and subsequent atmospheric precipitation removal are separate stages of an atmospheric sulfur budget.

The World Meteorological Organization coordinates international cooperation on atmospheric observations and their interpretation. Shared measurement conventions allow observations made by different services to be compared: instrument exposure, averaging intervals and reporting definitions can change the meaning of otherwise similar numbers.

Its instrument guide documents methods for measuring quantities such as pressure at a weather station.^[ref] The International Cloud Atlas by World Meteorological Organization similarly provides definitions for cloud and precipitation phenomena. Such conventions support physical comparison across observing networks; they do not remove instrument uncertainty or local sampling effects.

The National Oceanic and Atmospheric Administration is a United States scientific agency whose observations and research cover the atmosphere and oceans. Its measurement products connect meteorology, climatology and ocean circulation, with a stated observing method and reference period needed to interpret each product.

For example, its Arctic Oscillation index projects a measured atmospheric field onto a specified spatial pattern, while a climatological normal summarizes a different kind of information: statistics over a defined reference interval.^[ref][ref] Neither product is a direct measurement of one universal scalar called climate.

A lower-atmospheric low-pressure circulation associated with a warm air mass or heated land surface. Its strength and vertical structure depend on environmental constraints.

A lower-atmospheric high-pressure circulation associated with a cold dense air mass, often over a continent in winter. This does not imply the same circulation sign at all altitudes.

The Met Office is the United Kingdom's national meteorological service, producing observations, forecasts and climate information. Its scientific work connects instruments and numerical models: measurements constrain the present atmospheric state, while fluid and thermodynamic equations predict its evolution.

A concrete example is wind observation. The Met Office describes how cup anemometers and sonic anemometers measure local flow and why exposure and averaging conventions matter.^[ref] Its descriptions of the North Atlantic Oscillation also distinguish a large-scale circulation index from a deterministic forecast of weather at one site.

The temperature a parcel would have after reversible adiabatic compression to a reference pressure. For a dry ideal gas, $\theta =T(p_0/p{)}^{R/c_p}$; it is conserved for dry adiabatic motion.

A relatively warm, dry downslope wind on the lee side of a mountain. Condensation and condensate removal during ascent can produce precipitation-driven foehn warming; isentropic foehn drawdown, turbulent mixing and radiative warming can also contribute. Rainfall is therefore not a necessary condition for every foehn event. The atmosphere's upstream stratification, moisture and flow over or around the mountain determine the contributing mechanisms.^[ref]

The level where an initially unsaturated air parcel first reaches saturation during an approximately dry adiabatic ascent. Before saturation, expansion cools the parcel while its water-vapour mixing ratio remains approximately constant. At saturation, further ascent can condense water and release latent heat; the subsequent parcel lapse rate differs from the dry rate. Mixing with surrounding air changes this ideal parcel construction.

Correlated atmospheric variability between geographically separated regions. Wave propagation, mean-flow changes and coupled atmosphere–ocean forcing can produce physical connections, while statistical correlation alone does not identify a unique cause. A Rossby-wave teleconnection is an important large-scale pathway rather than an exhaustive definition of all teleconnections.

A comparatively narrow band of strong atmospheric flow. Tropospheric jets are associated with large horizontal temperature gradients through the thermal wind relation; strong potential vorticity gradients can guide Rossby waves. The background speed and its spatial variation control Doppler shifting and refraction of wave packets. Not every atmospheric jet has the same origin or altitude.

An anterior axial mesendodermal population with morphogenetic and signalling roles. In zebrafish its coherent migration depends on contact-mediated directional information.

alternating access is a transport mechanism in which a substrate-binding region becomes accessible to opposite sides of a membrane in different states. A continuously open pore is avoided; coupling the state sequence to a driving process permits active transport.

An adaptor protein complex couples membrane identity and cargo recognition to coat assembly. Coincident recognition of a membrane determinant, a cargo motif and coat partners helps restrict productive assembly to the appropriate site.