Chapter 2 Flashcards
Solar Wind
Clouds of ionized (charged) gases emitted by the Sun and travelling in all directions from the Sun’s surface.
Magnetosphere
Earth’s magnetic force field, which is generated by dynamo-like motions within the planet’s outer core.
How does the magnetosphere interact with solar wind?
The Magnetosphere deflects solar wind flow toward the poles so that only a small portion of it enters the upper atmosphere.
Types of Auroras
Aurora borealis (Northern lights) Aurora australis (Southern lights)
Auroras
Solar winds interact with the magnetosphere and gases in the ionosphere to create a light display at high latitudes.
Electromagnetic Spectrum definition
All the radiant energy produced by the Sun placed in an ordered range, divided according to wavelengths.
Wavelength
The distance between two corresponding points on any two successive waves. (Micrometers)
Frequency
The number of waves passing a fixed point per second.
Electromagnetic spectrum
Gamma Rays X-rays UltraViolet Visible (Purple to Red) Infrared Microwaves Radiowaves
Wien’s Displacement Law
All objects radiate energy in wavelengths related to their individual surface temperatures.
(the hotter the object, the shorter the mean wavelength of maximum intensity emitted)
Stefan Boltzmann Law
Objects that are efficient absorbers of radiation are good emitters too.
Blackbody Radiator
A blackbody is a perfect absorber of radiant energy; it absorbs and subsequently emits all the radiant energy that it receives.
3 Radiation Laws
- All objects above zero degree Kelvin emit radition
- Wien’s Displacement Law
- Stefan Boltzmann Law
Aphelion
when Sun and Earth are farthest apart (July 4 )
Perihelion
when Sun and Earth are closest together (January 3)
Solar Declination
The latitude of the subsolar point.
Migrates annually through 47 degrees of latitude between the Tropics of Cancer (23.5° N) and Capricorn (23.5° S).
Solar Elevation
SEE LAB MANUAL
Subsolar Point
place on Earth at which the Sun is “directly” overhead (perpendicular, at a 90° angle)
Equinoxes
The time or date (twice each year) at which the sun crosses the equator. Day-length is equal for all latitudes on Earth.
- Spring Equinox: March 20-21
- Fall Equinox: Septemper 22-23
Summer/June Solstice
The subsolar point is on the Tropic of Cancer (23.5°N).
- Daylength is longest for the Northern Hemisphere latitudes, Shortest for Southern Hemisphere latitudes.
Summer/June Solstice
The subsolar point is on the Tropic of Cancer (23.5°N).
Day-length is longest for the Northern Hemisphere latitudes. Marks the beginning of summer.
The North Pole is within the circle of illumination (receives 24 hours of sunlight)
Winter/December Solstice
The subsolar point is on the Tropic of Capricorn (23.5°S).
- Daylength is shorted for the Northern Hemisphere latitudes. Marks the beginning of winter.
- The North Pole is within the circle of illumination (receives 24 hours of night)
SEASONAL VARIATION RESULTS FROM EARTH’S FOLLOWING PHYSICAL CHARACTERISTICS (5)
REVOLUTION
ROTATION
TILT
AXIAL PARALLELISM
SPHERICITY
REVOLUTION
Earth’s orbital movement around the sun (365.24 days to complete)
REVOLUTION’s role in seasonality
Determines the length of the year and the seasons.
ROTATION
Earth turning on its axis (approximately 24 hours to complete)
ROTATIONs role in seasonality
Determines day–night insolation variation.
TILT
Alignment of axis at about a 23.5° angle from perpendicular to the plane of the ecliptic (the plane of Earth’s orbit).
TILT’s role in seasonality
Summer happens (NH) when the Northern hemisphere is tilted towards the Sun, and winter happens in the hemisphere is tilted away from the Sun.
AXIAL PARALLELISM
Fixed axial alignment, with Polaris directly overhead at the North Pole throughout the year.
AXIAL PARALLELISM’s role in seasonality
Earth’s axis remains aligned the same throughout the year (it “remains parallel to itself”); thus, the axis extended from the North Pole points into space always near Polaris, the North Star.
SPHERICITY
Oblate spheroidal shape lit by Sun’s parallel rays (geoid)
SPHERICITY’s role in seasonality
Earth’s spherical shape causes the parallel rays of the Sun to fall at uneven and varying angles on Earth’s surface. The curvature means that insolation angles and net radiation received vary between the equator and the poles.
The equator receives
equal hours of day and night, year round.
SEASONALITY
Refers to the seasonal variation of the Sun’s position above the horizon and to changing day-lengths during the year.
SEASONAL VARIATION RESULTS FROM (SUN)
Variations in the:
Sun’s altitude above the horizon
Sun’s declination
Daylength during the year
Why is the distance between earth and sun inconstant?
the orbit is elliptical
the sun is slightly off-center
