Instrument aboard SOHO satellite which analyzes the constituents of the solar wind. Top

The north-south meridian of the Sun that passes through the center of the disc as viewed from the Earth. Top

Negative Cloud-to-Ground Lightning. Electrical discharge from cloud to ground, which transfer negative charges(electrons) from a negatively charged region within the cloud to the ground. Top

Positive Cloud-to-Ground Lightning. Electrical discharge from cloud to ground, who transfer positive charges from a positively charged region within the cloud to the ground, which is equivalent to the transport of electrons from the ground to the cloud. Top

The currents that flow on the magnetopause make up the CF current system. Top

Layer where ionic loss is a linear function of the electronic concentration. Top

Layer where ionic loss is a quadratic function of the electronic concentration. Top

It is comprised of an array of imaging pixels and a matching array of storage pixels that are coupled together. After the imaging array is exposed to light, its charges are quickly transferred to the storage array. While the imaging CCDs are being exposed to the next picture, the storage CCDs from the last picture are being read out a row at a time to the analog-to-digital converters (A/D converters) that transform the charges into binary data to be processed. Top

The irregular layer of the solar atmosphere that is located above the photosphere and beneath the corona. The temperature in the chromosphere rises from 6,000° C to about 20,000° C. It is hotter than the photosphere but not as hot as the corona. Top

It is a bright area seen in chromospheric lines most of the time surrounding one or several sunspots. Chromospheric plage is one of the main components of the solar activity. Top

Is an elliptic orbit with eccentricity equal to 0. A rotation around a fixed axis, which the line trough the center of mass perpendicular to the lane motion. Top

The flow, or movement, of a fluid (e.g., water or air) in or through a given area or volume. Top

A cirriform cloud characterized by thin, white patches, each of which is composed of very small granules or ripples. These clouds are of high altitude (6,000 -12,000 m). Top

A cloud of a class characterized by a composition of ice crystals and often by the production of halo phenomena and appearing as a whitish and usually somewhat fibrous veil, often covering the whole sky and sometimes so thin as to be hardly discernible. These clouds are of high altitude (6000 -12,000 m). Top

(CI) High-level clouds (8,000 m or higher), composed of ice crystals and appearing in the form of white, delicate filaments or white or mostly white patches or narrow bands. Cirrus clouds typically have a fibrous or hairlike appearance, and often are semi-transparent. Top

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time. Top

It is, in a narrow sense, usually defined as the "average weather," or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. Top

It is a change in the statistical distribution of weather over periods of time that range from decades to millions of years. Top

Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the climate system to projections of future climate. Top

An interactive system consisting of five major components - the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere, forced or influenced by various external forcing mechanisms, the most important of which is the Sun. Also the direct effect of human activities on the climate system is considered an external forcing. Top

The study of climate, scientifically defined as weather conditions averaged over a period of time, and it is a branch of the atmospheric sciences. Top

A visible cluster of tiny water and/or ice particles in the atmosphere. Top

A type of radar that extracts additional information about a target through measurement of the phase of echoes from a sequence of pulses. The phase information may be used to improve the signal-to-noise ratio, to estimate the velocity of the target through the Doppler effect, or to resolve the location of the target in a synthetic aperture radar. Top

The complementary, in spherical coordinates, of a latitude. Top

A Small Solar System Body that orbits the Sun. Comet nuclei are themselves loose collections of ice, dust and small rocky particles, ranging from a few kilometers to tens of kilometers across. Top

Change of physical state of matter from gaseous phase into liquid phase, which depend on balance between pressure and temperature. Top

Flow of heat in response to a temperature gradient within an object or between objects that are in physical contact. Top

It is the material capability to conduct an electric current or heat. Top

In geomagnetism, conjugate points have the same magnitude of geomagnetic field, they are in same geomagnetic line, and they are in opposite geomagnetic hemispheres. Top

Low value but long duration electric current establishing a persistent connection between the center of charge within the cloud and the ground after the main discharge of a lightning flash. Most charge of a lightning flash transferred to ground (tens of coulombs) is due to this current. Top

The approximate temperature that the air near the ground must warm to in order for surface-based convection to develop, based on analysis of a sounding. Top

The convective zone of a star is the range of radii in which energy is transported primarily by convection. Stellar convection consists of mass movement of plasma within the star which usually forms a circular convection current with the heated plasma ascending and the cooled plasma descending. Top

Approximation of a set amount, or a point or state of equilibrium. Tendency to approach a common limit. Top

The region of very high density and temperature located at the center of the Sun. Top

A fictitious force used to account for the apparent deflection of a body in motion with respect to the Earth, as seen by an observer on the Earth. The deflection (to the right in the Northern Hemisphere) is caused by the rotation of the Earth. Top

The outer atmosphere of the Sun with low density and high temperature. Visible as an extended bright region about the Sun during solar eclipses. Top

A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved. Top

An ultraviolet spectrometer aboard SOHO satellite. Top

A low density region of the corona with relatively low temperature. Coronal holes are associated with unipolar photospheric regions and, for this reason, sources of high speed solar wind streams. The magnetic field lines in a coronal hole extend out into the solar wind rather than coming back down to the Sun's surface as they do in other parts of the Sun. Top

An ejection of material from the Sun into interplanetary space. If the material is directed towards the Earth then the event may result in a disturbance to the Earth's magnetic field and ionosphere. Top

Globules of gas seen in Hα light descending along curved paths to the chromosphere. They are the final stage in the development of loop prominences, which are produced by a large flare on the Sun's limb. Several hours after the flare has occurred, the prominence breaks up into fragments which descend along the outline of the now-invisible loop as coronal rain. Top

Coronal transients are the main evolutionary dynamical structures in the extended solar corona. Such phenomena are associated with a variation of the physical parameters (temperature, density and velocity) characterizing the coronal plasma, occurring over typical time scales ranging from tens of minutes to hours. Top

Measure of the similarity between two variables. Top

Energetic charged particles originating from outer space that impinges on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, almost 10% are helium nuclei (alpha particles), and slightly less than 1% are heavier elements and electrons (beta minus particles). Top

The highest frequency that can be reflected vertically from an ionospheric layer. Top

Electric current created by the separation of charges in the magnetosphere tail (night side of the Earth). This current, like others in the magnetosphere, is driven by energy extracted from the solar wind. Top

Dense clouds that form in unstable air and especially in the lower troposphere, which are built in blocks or cells isolated or grouped. They grow vertically stack ("Cumulus" in Latin) to high altitudes indicate storms. Top

SEE Polar Cusp Top