Radio Detection And Ranging. It is system for locating objects by sending radio waves and recording their echoes.

Component of motion toward or away from a given location. It is the component of motion parallel to the radar beam.

A measure of the intensity of the radiant energy flux emitted by a body in a given direction.

Regions of the magnetosphere roughly 1.2 to 6 Earth radii above the equator in which charged particles are stably trapped by closed geomagnetic field lines. There are two belts. The inner belt is part of the plasmasphere and corotates with Earth. The outer belt extends on to the magnetopause on the sunward side (10 Earth radii under normal quiet conditions) and to about 6 Earth radii on the nightside.

It is the pressure exerted upon any surface exposed to electromagnetic radiation.

Internal region of the Sun, between the nuclear oven and the convection zone. Here, the energy produced by the nuclear core is transmitted by radiation.

Electromagnetic emission of the Sun which wavelengths can vary from centimeters to decameters, under both quiet and disturbed conditions.

The Sun emits radio waves. The intensity of the radio emission from the Sun often increases during solar flares (radio bursts) and above large sunspot groups (radio noise storms). In addition, the Sun produces a background radio flux which depends on frequency and varies in the course of the solar cycle. Units for solar radio flux are 1E-22 watts per square meter per Hertz (also known as a solar flux unit or s.f.u.)

It is a technique to perform atmospheric measurements and can be used as a weather forecasting tool, and in monitoring climate change. RO consist on calculate the refraction index of the medium by following the path of the radio signal. With the refraction index and some more variables, measured at the atmosphere by other ways, the entire configuration can be obtained.

Electromagnetic waves occurring on the radio frequency portion of the electromagnetic spectrum (10 kHz- 300 GHz).

Information of radar measurements where the colobar represents the mean Doppler, saturation the spectral width, and lightness the signal-to-noise ratio of the echoes.

The scattering of light by particles and molecules which are much smaller than the wavelength of the light.

It is instability of an interface between two fluids of different densities, which occurs when the lighter fluid is pushing the heavier fluid.

It is a negatively charged leader retracing a previously positively charged channel. It propagates backwards towards the region of the initiation of a lightning flash.

The bonding of ions and free electrons to form neutral atoms and molecules. It can leave its products in excited states.

A plasma process by which differently directed field lines link up, allowing topological changes of the magnetic field to occur, determining patterns of plasma flow, and resulting in conversion of magnetic energy to kinetic and thermal energy of plasma. Reconnection is invoked to explain the energization and acceleration of the plasmas that are observed in coronal mass ejections, magnetic substorms, and elsewhere in the solar system.

Zone of the magnetosphere, on the night side, where the plasma sheet encounters the magnetopause.

A disturbance (usually geomagnetic) which repeats at an interval of approximately 27 days, the approximate rotation rate of some features on the Sun.

Although a radio wave is actually refracted in the ionosphere, it is often permissible to substitute a simple triangular ray path for the real ray path, as if the ray were reflected from a mirror. Thus radio waves are often referred to as being reflected from the ionosphere.

It is the fraction of incident radiation reflected by a surface.

The bending of a wave when it crosses a boundary between media due to a change in velocity of the wave. Until it reaches the ionosphere, a radio wave propagates in a straight line. Once in the ionosphere, it may be refracted back towards the ground. The amount of refraction depends on the electron density of the ionosphere and the operating frequency.

An index to define the amount of refraction a wave will undergo when it enters a medium.

The bending or change in direction of propagation of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density.

The driving currents that flow down into the positively charged region of the high-latitude dawnside auroral zone an up from the negative region of the high-latitude duskside auroral zone.

Which are the shielding that have the opposite sense from region 1 and flow in and out of the lower-latitude regions of the auroral zone.

The state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus is the same, or nearly the same, as the natural vibration frequency of the system.

The delay in propagation of a radio wave near the critical frequency caused by the slowing down of the wave by the ionosphere.

A ground potential wave that propagates continuously up the previously ionized and charged leader path

An electric current that creates a ring at low latitude around the Earth, at between four and seven terrestrial radii from the surface of the planet.

It is an instrument used to quantify the amount of electromagnetic wave ionospheric absorption in the atmosphere.

They are short-lived (minor45 min) gravity waves, small-scale wave patterns of restricted spatial extent, and are thought to be generated in-situ by localized shear or convective-type instabilities in the background wind field.

SEE Radio Occultation.

The Rossby number is a dimensionless number used in describing fluid flow and is the ratio of inertial to Coriolis force. It is commonly used in geophysical phenomena in the oceans and atmosphere, where it characterizes the importance of Coriolis accelerations arising from planetary rotation.

The movement of ridges and troughs in the upper wind patterns, primarily the jet stream.

(after Lord Rayleigh and G. I. Taylor), is an instability of an interface between two fluids of different densities, which occurs when the lighter fluid is pushing the heavier fluid.