Ice cores

Core sample from the accumulation of snow and ice over many years that have re-crystallized, trapping air bubbles from previous time periods.

Ice crystal model

Ice crystals

Macroscopic crystalline form of ice, which has the shape of hexagonal columns and plates, dendritic crystals, needles and their combinations. They form at very low temperature (0°F/-18°C or less) in stable atmosphere.

Ice pellets

Type of precipitation consisting of transparent or translucent particles of ice, of 5 mm or less in diameter. Their form may be spherical, irregular or eventually conical. They include two basic types: sleet and small hail.

Ice storm

Strom characterized by the fell liquid precipitation that freezes on impact on terrestrial objects, creating a coat of glaze on them.


Sign which refers to the object that it represents by virtue of characteristics of its own. Recognizable image of the object that the sign represents.


Electronic device that detects electromagnetic radiation with spatial resolution.


Acute contagious viral infection characterized by inflammation of the respiratory tract, with fever, muscle pain, chills. It can be less severe, but it always brings fever and respiratory involvement.

Infrared radiation

Portion of the electromagnetic spectrum between visible light and microwaves, that is between 0.75 and 1000 µm.


Incoming solar radiation.

Interglacial period

Period characterized by relatively mild climate within an ice age.

Intertropical convergence zone / ITCZ, Equatorial convergence zone

Narrow zone where the southeast trades (of the Southern Hemisphere) and the northeast trades (of the Northern Hemisphere) meet.

Intertropical front / Equatorial front, tropical front

Quasi-permanent front that exists within the equatorial trough, separating the Northern and Southern Hemispheric trade winds or marking the extreme limit of a tropical monsoon.


Atmospheric region, located in the upper mesosphere and good part of the thermosphere, which contains significant concentrations of ions and electrons in sufficient quantities to reflect electromagnetic waves.

Irisation or iridescence

Colors appearing on clouds, sometimes mingled, sometimes in the form of bands nearly parallel to the edges of the clouds. Green and pink predominate, often with pastel shades. The cause is sunlight being diffracted by cloud particles


Line that joins points of equal or constant pressure on a given reference surface (such as mean sea level on surface charts), usually drawn at intervals of one millibar or more.