IRIDESCENCE
– brilliant patches of green or pink sometimes seen near the edges of high- or medium-level clouds.
ISALLOBAR
– A line of equal surface pressure change.
ISENTROPIC LIFT
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ISOBAR
– A line of equal barometric pressure on a weather map.
ISODROSOTHERM
– A line of constant dewpoint temperature.
ISOHYET
– A line of equal rainfall.
ISOLATED
– Showers covering less than 15 percent of an area.
ISOPLETH
– A line of a constant meteorological value.