Lecture 5 - Solar Energy to Earth and the Seasons & Earth’s Modern Atmosphere Flashcards
What is the sun?
A star located in the Orion Spur of the Sagittarius Arm, which sustains a nuclear fusion reaction at its core to produce radiant energy.
How is solar energy produced?
Hydrogen atoms are forced together to produce helium, and energy is released.
What is the importance of solar energy?
The ultimate energy source for most life processes in our biosphere.
What is a solar cycle?
The periodic variation in the sun’s activity and appearance over time.
Define sunspots.
Disturbances on the surface of the Sun caused by magnetic storms.
What are solar minimum and solar maximum?
Solar minimum is a period of years with few sun spots, while solar maximum is a period of years when sun spots are numerous.
Define solar flares.
Magnetic storms that cause surface explosions and prominence eruptions (outbursts of gasses arcing from the surface), which often occur near sunspots.
What is solar wind?
Clouds of electrically charged particles emitted by the sun that surge outward in all directions from the Sun’s surface (corona).
How does the Earth’s magnetic field protect us?
It deflects the solar wind toward both of Earth’s poles.
What are coronal mass ejections (CMEs)?
Massive outbursts of charged materials that are part of the solar wind.
What is the effect of coronal mass ejections?
Create auroras in the upper atmosphere near the poles (Aurora borealis and Aurora Australis).
What are the effects of solar winds on telecommunication systems?
Solar winds can disrupt radio broadcasts and satellite transmissions and cause overloads on Earth-based electrical systems.
Define thermopause.
The outer boundary of the Earth’s energy system.
Define insolation.
The solar radiation that is intercepted by Earth (incoming solar radiation).
Define solar constant.
The average insolation received at the thermopause when Earth is at its average distance from the Sun.
Define subsolar point.
The point on the earth’s surface where insolation arrives perpendicular to the surface.
What are the three things that can happen to solar radiation?
Scattering, absorption, and reflection.
Define seasonality.
1) the seasonal variation of the Sun’s position above the horizon 2) changing day-lengths during the year.
What causes seasonal variations?
Changes in the sun’s altitude, or angle between the sun and the horizon.
Define the sun’s declination.
The latitude of the subsolar point, between the Tropic of Cancer and the Tropic of Capricorn.
What are the three variations that result in seasons?
1) the Sun’s altitude above the horizon, 2) the sun’s declination (latitude of the subsolar point), 3) day-length during the year.
Define solstice and equinox.
When the sun’s subsolar point is on the Tropic of Cancer or the Tropic of Capricorn, it is the Solstice. When the sun’s subsolar point is on the equator, it is the Equinox, days and nights are of equal length.
How does day-length vary?
Varies everywhere, except at the equator, which always receives equal hours of day and night and at the poles, which have 6 months of day and 6 months of night.
What are the three main aspects of the Earth’s atmosphere?
Composition, temperature, and function.
