Glossary and Acronyms: I

ICAO:

International Civil Aviation Organization. The atmosphere named IACO is a standard atmopshere which the main characteristics are: MSLP: 1013,25 hPa, vertical gradient of temperature:6,5°C/km from the surface to the tropopause, located at 11 km.

Instability:

property of the state of rest or continuous movement of a system such that any disturbance to this state will grow. In meteorology, the term is often used as a synonym for static instability that is the hydrostatic state of the atmosphere in which a particle of air moved from its initial level undergoes a hydrostatic force which tends to remove it farther from this level.
An unstable air mass is the place where upward movements and convection occur.

Inversion layer:

atmospheric layer in which the temperature increases or remains constant with height.

Inverted barometer effect:

adjustment of sea level to changes in barometric pressure. In the case of full adjustment, a decrease in barometric pressure of 1 mb corresponds to a rise in sea level of 1cm (an increase in barometric pressure of 1 mb corresponds to a fall in sea level of 1cm).
A bigger rise in sea level can occur due to the local bathymetry when a tropical system approaches.

IPCC:

Intergovernmental Panel on Climate Change. The IPCC is the leading body for the assessment of climate change, established in 1988 by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of climate change and its potential environmental and socio-economic consequences.

The Intergovernmental Panel of Climate Change is the leading body for the assessment of climate change, established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of climate change and its potential environmental and socio-economic consequences.

The IPCC is a scientific body. It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate related data or parameters. Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis. Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information. Differing viewpoints existing within the scientific community are reflected in the IPCC reports.

The IPCC is an intergovernmental body, and it is open to all member countries of UN and WMO. Governments are involved in the IPCC work as they can participate in the review process and in the IPCC plenary sessions, where main decisions about the IPCC workprogramme are taken and reports are accepted, adopted and approved. The IPCC Bureau and Chairperson are also elected in the plenary sessions.

Because of its scientific and intergovernmental nature, the IPCC embodies a unique opportunity to provide rigorous and balanced scientific information to decision makers. By endorsing the IPCC reports, governments acknowledge the authority of their scientific content. The work of the organization is therefore policy-relevant and yet policy-neutral, never policy-prescriptive.

IR (InfraRed):

The infrared radiation is that portion of the electromagnetic spectrum lying between visible light and microwaves. The wavelength range is approximately between 0.75 and 1000 μm. In meteorology, this range is often further divided into the solar infrared and terrestrial radiation, with the division occurring around 4 μm. Dominant absorbers of infrared radiation include the Earth's surface, clouds, water vapor, and carbon dioxide.
An infrared image is a satellite imagery sensed in the 3-13-μm wavelength region of the electromagnetic spectrum. Usually refers to the thermal infrared, particularly the 10-12.5-μm window. It gives a thermal picture of the clouds tops (available night and day).
The near-infrared radiationis the preferred term for the shorter wavelengths in the infrared region of the electromagnetic spectrum extending from about 0.75 μm (visible red) to around 3 μm.

ITCZ:

InterTropical Convergence Zone. Also called equatorial convergence zone. Narrow zone where the trade winds of the two hemispheres meets (the southeast trades and the northeast trades (of the Southern and Northern Hemispheres, respectively)). It is collocated with the ascending branch of the Hadley cell, and therefore the place of low pressure and high extent clouds (Cumulonimbus). It moves into or toward the summer hemisphere.

Isobare:

line joining points of equal pressure on a surface (level surface, vertical cross-section, etc ...)

Isohyet:

line joining points of equal precipitation amount recorded during a specific period.

Isohypse:

line joining points of equal geopotential height on a particular surface, generally an isobaric surface.

Isotach:

line joining points of equal wind speed.