Earth phenomena

El Niño /ɛl ˈniːnjoʊ/ (Spanish pronunciation: [el ˈniɲo]) is the warm phase of the El Niño Southern Oscillation (commonly called ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (between approximately the International Date Line and 120°W), including off the Pacific coast of South America.

Sea ice arises as seawater freezes.

Melt ponds are pools of open water that form on sea ice in the warmer months of spring and summer.

An aurora, sometimes referred to as a polar light, is a natural light display in the sky, predominantly seen in the high latitude (Arctic and Antarctic) regions.

The polar night occurs when the night lasts for more than 24 hours.

Sunrise or sun up is the instant at which the upper edge of the Sun appears over the eastern horizon in the morning.

Sunset or sundown, is the daily disappearance of the Sun below the western horizon as a result of Earth's rotation.

A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain.

Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes and is deposited on the leeward (downwind) shores.

Asian Dust (also yellow dust, yellow sand, yellow wind or China dust storms) is a meteorological phenomenon which affects much of East Asia year round but especially during the spring months.

The equation of time describes the discrepancy between two kinds of solar time.

Twilight is the illumination of the Earth's lower atmosphere when the Sun itself is not directly visible because it is below the horizon.

Alexander's band or Alexander's dark band is an optical phenomenon associated with rainbows which was named after Alexander of Aphrodisias who first described it in 200 AD.

The blue hour (from La hora azul, in Spanish, or L'Heure Bleue in French) is the period of twilight early in the dawn each morning and late dusk each evening when the sun is at a significant distance below the horizon and the residual, indirect sunlight takes on a predominantly blue hue.

A natural phenomenon is an observable event which is not man-made.

Measurement of sea ice is important for safety of navigation and for monitoring the environment, particularly the climate.

Dusk occurs at the darkest stage of twilight, or at the very end of astronomical twilight just before night.