Autumn Air

Autumn

Autumn, also known as fall in North American English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, beginning in September or March. Autumn is the season when the duration of daytime becomes noticeably shorter and the temperature cools considerably. Day length decreases and night length increases as the season progresses until the winter solstice in December and June. One of its main features in temperate climates is the striking change in colour of the leaves of deciduous trees as they prepare to shed.

Atmosphere of Earth

The atmosphere of Earth consists of a layer of mixed gas that is retained by gravity, surrounding the Earth's surface. It contains variable quantities of suspended aerosols and particulates that create weather features such as clouds and hazes. The atmosphere serves as a protective buffer between the Earth's surface and outer space. It shields the surface from most meteoroids and ultraviolet solar radiation, reduces diurnal temperature variation – the temperature extremes between day and night, and keeps it warm through heat retention via the greenhouse effect. The atmosphere redistributes heat and moisture among different regions via air currents, and provides the chemical and climate conditions that allow life to exist and evolve on Earth.

autumn

Noun

1. Traditionally the third of the four seasons, when deciduous trees lose their leaves, and temperatures and daylight hours decrease; typically regarded as spanning the months of September, October, and November in the Northern Hemisphere, and the months of March, April and May in the Southern Hemisphere.
2. The time period when someone or something is past its prime.

Verb

1. To spend the autumn (in a particular place).
2. To (cause to) undergo the changes associated with autumn, such as leaves changing color and falling from trees.

air

Symbol

1. ISO 639-3 language code for Airoran.

Noun

1. The substance constituting Earth's atmosphere: a gaseous mixture of nitrogen, oxygen, and various trace gases.
2. The substance of the atmosphere seen as an agency of freshness.