ch.3 Earth-Sun Relationships & Solar Energy terms Flashcards

Terms Definitions
a diagram that shows the declination of the sun throughout the year.
angle of inclination
tilt of Earth's polar axis at an angle of 23½ from the vertical to the plane of the ecliptic.
Antarctic circle
parallel of latitude at 66½°S; the northern limit of the zone in the Southern Hemisphere that experiences a 24-hour period of sunlight and a 24-hour period of darkness at least once a year.
position of Earth's orbit at farthest distance from the sun during each Earth revolution.
Arctic circle
parallel of latitude at 66½°N; the southern limit of the zone in the Northern Hemisphere that experiences a 24-hour period of sunlight and a 24-hour period of darkness at least once a year.
sometimes called a minor planet; any solar system body composed of rock and/or metal not exceeding 500 miles in diameter.
colorful interaction of solar wind with ions in Earth's upper atmosphere; more commonly seen in higher latitudes. Called aurora borealis in the Northern Hemisphere (also known as the northern lights), and the aurora australis (southern lights) in the Southern Hemisphere.
amount of heat necessary to raise the temperature of 1 gram of water 1°C.
centrifugal force
force that pulls a rotating object away from the center of rotation.
circle of illumination
line dividing the sunlit (day) hemisphere from the shaded (night) hemisphere; experienced by individuals on Earth's surface as sunrise and/or sunset.
a small body of icy and dusty matter that revolves about the sun. When a comet comes near the sun, some of its material vaporizes, forming a large head and often a tail.
the latitude on Earth at which the noon sun is directly overhead.
electromagnetic energy
all forms of energy that share the property of moving through space (or any medium) in a wavelike pattern of electric and magnetic fields; also called radiation.
one of two times each year (approximately March 21 and September 22) when the position of the noon sun is overhead (and its vertical rays strike) at the equator; all over Earth, day and night are of equal length.
fusion (thermonuclear reaction)
the fusing together of two hydrogen atoms to create one helium atom. This process releases tremendous amounts of energy.
galactic movement
movement of the solar system within the Milky Way Galaxy.
a large assemblage of stars; a typical galaxy contains millions to hundreds of billions of stars.
geostationary orbit
an orbit that synchronizes a satellite's position and speed with Earth rotation so that it continually images the same location.
giant planets
the four largest planets—Jupiter, Saturn, Uranus, and Neptune.
the mutual attraction of bodies or particles.
incoming solar radiation, that is, energy received from the sun.
a family of U.S. satellites that have been returning digital images since the 1970s.
light year
the distance light travels in 1 year—6 trillion miles.
longwave radiation
electromagnetic radiation emitted by Earth in the form of waves more than 4.0 micrometers in amplitude, which includes heat reradiated by Earth's surface.
a measure of the total amount of matter in a body.
the luminous phenomenon observed when a small piece of solid matter enters Earth's atmosphere and burns up.
any fragment of a meteor that reaches Earth's surface.
tendency of Earth's polar axis to remain parallel to itself at all positions in its orbit around the sun.
position of Earth at closest distance to sun during each Earth revolution.
plane of the ecliptic
plane of Earth's orbit about the sun and the apparent annual path of the sun along the stars.
any of the nine largest bodies revolving about the sun, or any similar bodies that may orbit other stars.
revolution (Earth)
motion of Earth along a path, or orbit, around the sun. One complete revolution requires approximately 365¼ days and determines an Earth year.
rotation (Earth)
turning of Earth on its polar axis; one complete rotation requires 24 hours and determines one Earth day.
any body that orbits a larger primary body, for example, the moon orbiting Earth.
shortwave radiation
radiation energy emitted by the sun in the form of waves of less than 4.0 micrometers (1 micrometer equals one ten thousandth of a centimeter); includes X-rays, gamma rays, ultraviolet rays, and visible light waves.
solar constant
rate at which insolation is received just outside Earth's atmosphere on a surface at right angles to the incoming radiation.
solar energy
energy derived from the sun in the form of solar radiation.
solar system
the system of the sun and the planets, their satellites, comets, meteoroids, and other objects revolving around the sun.
solar wind
streams of hot ions (protons and electrons) traveling outward from the sun.
one of two times each year when the position of the noon sun is overhead at its farthest distance from the equator; this occurs when the sun is overhead at the Tropic of Cancer (about June 21) and the Tropic of Capricorn (about December 21).
visible dark (cooler) spots on the surface of the sun; their numbers seem to follow an approximate 11-year cycle.
Tropic of Cancer
parallel of latitude at 23½°N; the northern limit to the migration of the sun's vertical rays throughout the year.
Tropic of Capricorn
parallel of latitude at 23½°S; the southern limit to the migration of the sun's vertical rays throughout the year.
vertical rays
sun's rays that strike Earth's surface at a 90° angle.
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