Day: August 20, 2022

Aphelion The point on the earth’s orbit that is farthest from the sun. Although the position is part of a 21,000 year cycle, currently it

Apogee The point farthest from the earth on the moon’s orbit. This term can be applied to any other body orbiting the earth, such as

Arid A term used for an extremely dry climate. The degree to which a climate lacks effective, life-promoting moisture. It is considered the opposite of

Atmosphere The gaseous or air portion of the physical environment that encircles a planet. In the case of the earth, it is held more or

Atmospheric Pressure The pressure exerted by the atmosphere at a given point. Its measurement can be expressed in several ways. One is in millibars. Another

Autumn The season of the year which occurs as the sun approaches the winter solstice, and characterized by decreasing temperatures in the mid-latitudes. Customarily, this

Ball Lightning A relatively rare form of lightning consisting of a luminous ball, often reddish in color, which moves rapidly along solid objects or remains

Barometer An instrument used to measure atmospheric pressure. Two examples are the aneroid barometer and the mercurial barometer. Atmospheric Pressure The pressure exerted by the

Barometric Pressure The pressure exerted by the atmosphere at a given point. Its measurement can be expressed in several ways. One is in millibars. Another

Biosphere The transition zone between the earth and the atmosphere within which most terrestrial life forms are found. It is considered the outer portion of