Geo 3

The earth is approximately ___% the size of the sun.

1%

Tropics are measured at

23. Degrees north or south

Tilt of the earth from the ecliptic plane (Axial told angle) is

23.5 degrees

One rotation takes exactly _____ and is called a mean solar day

24 hours

The amount of energy received by the earth depends on

3 Earth-Sun Relationships

The amount of energy received varies across the globe depending on

3 earth - sun relationships

Our eyes see

400 - 700 Hz and help us interpret color via visible light

Solar angles

Angles at which the sun hits the Earth

Beam spreading

At noon on the equinox

Earth's speed

Because of rotation, the Earth's surface moves at the equator at a speed of about 467 m per second or slightly over 1675 km per hour

The only way energy can travel through the vacuum of space is

By radiation

Net radiation

Cumulative radiation from the day

Atmospheric Beam Depletion

Different from beam spreading but has the same cause. At higher latitudes, the sun's beams must pass through more of the atmosphere because there is a smaller solar angle. Some incoming energy is reflected or scattered, leaving less to reach the surface.

Solar angle and beam spreading

Direct vs Oblique Direct = 2.5x more energy than poles annually

Earth's rotation on it's axis causes

Diurnal Cycle of Day and Night Which affects temperature, shadows, & light

equinox, poles, solstice

During the two equinoxes, the circle of illumination cuts through the North Pole and the South Pole. On the June solstice, the circle of illumination is tangent to the Arctic Circle (66.5° N) and the region above this latitude receives 24 hours of daylight. The Arctic Circle is in 24 hours of darkness during the December solstice.

The orbit of the Earth around the Sun is called an _______. This celestial motion takes 365.26 days to complete one cycle.

Earth revolution

All things above absolute zero emit

Electromagnetic energy / radiation due to their vibrating molecules.

Latitude 0

Equator

Equinox

For both hemispheres, the Earth is 90 degrees away from the sun around March 21 and then again around September 21. This corresponds to the Fall and Spring Equinox (equinox is Latin for "equal night"). Everyplace in the world has about 12 hours of daylight and 12 hours of night.

Solstice

For the Northern Hemisphere, the axis points most toward the Sun in June (specifically around June 21), and away from the Sun around December 21. This corresponds to the Winter and Summer Solstice (solstice is Latin for "the sun stands"), or the midpoints of winter and summer. For the Southern Hemisphere, this is reversed.

EMR; Adding energy increases

Frequency

South Pole is pointing

Further from the sun

EMR One wave / cycle per second is measured as

Hz (frequency)

Subsolar Declination

Is the latitude of the Subsolar point

The amount of energy contained within specific radiation is determined by

It's wavelength

June Solstice

June 21st The northernmost solar declination Day of greatest insolation in the northern hemisphere The shortest day for the Southern Hemisphere

The electromagnetic spectrum spans from measurements in

Kilometers to nanometers

Radiation is a form of _____ energy

Kinetic

Latitudes

Latitude affects the amount of energy from insolation. Higher latitudes experience more beam spreading. Lower latitudes experience less beam spreading. Higher latitudes experience more atmospheric beam depletion. Lower latitudes experience less atmospheric beam depletion. At higher latitudes, less energy is received over the course of a year than at lower latitudes.

Longer EMR =

Less energy

Equinox

Means "equal night" where everyone on earth has 12 hours of darkness on this day. Occurs on March 21 and September 21. Solar declination is zero degrees.

Shorter EMR wavelength =

More energy

North Pole is pointing

More toward the sun

Tropic of Cancer

Northern most solar declination that occurs on June 21

Beam spreading on June Solstice

Part of earth Dark for 24 hours

The earth's axis points toward ____ with a ___ degree tilt.

Polaris with a 23.5 degree tilt.

______ from the sun travels through the vacuum of space, passes through the Earth's atmosphere and is absorbed by the surface

Radiation

Chichen-Itza (1000 AD)

SW corner points to the rising summer solstice sun NW corner points to the setting winter solstice sun

Beam spreading

Same amount of energy (that was spread over a small area such as at noon) spreading over a large area (such as during sunset, sunrise, or seasonal low sun angle.) Daily changes due to rotation Seasonal changes due to tilt and location in orbit

Axial Orientation / Axis Tilt is responsible for

Seasons

The north pole

Since the tilt of the axis is 23 1/2 degrees, the north pole never points directly at the Sun, but on the summer solstice it points as close as it can, and on the winter solstice as far as it can.

What determines how much energy reaches the Earth's surface?

Solar angle - beam spreading Atmospheric beam depletion Period of daylight (As a result of the earth's changing orientation to the sun)

Solstices

Solar stand still (reaches as far north or as fall south as it will go)

December Solstice

Southernmost solar declination Day of greatest insolation in the northern hemisphere The shortest day for the Northern Hemisphere

2 Radiation Laws

Stefan Boltzmann Law & Wien's Law

When the Earth's axis points towards the Sun, it is ______ for that hemisphere.

Summer (opposite = winter)

Arctic Circle

Sun directly overhead at the Tropic of Cancer 23 degrees north.

For all dates, minimum temperature occurs at

Sunrise

Why does the tilt of earth's axis matter to our climate?

The density of light drops. In other words, the amount of light per square centimeter drops (the number of square centimeters increases, while the total amount of light stays the same).

The elliptical rotation causes

The earth is not always the same distance from the sun. It varies by 5 million km which causes a 6% difference in energy.

3 important Earth-Sun relationships

The earth rotates on it's axis The earth revolves around / orbits the sun The earth tilts on it's axis

Equal

The equator experiences equal day and night on every day of the year. Day and night is also of equal length for all Earth locations on the September and March equinoxes.

Ecliptic Plane

The plane on which the earth revolves around the sun

Subsolar Point

The point on earth directly under the sun

All EMR travels at this speed

The speed of light

_____ is the source of energy that drives the Earth's climate system.

The sun

Since we know the sun is hotter than the earth, we can conclude that

The sun emits much more radiation than the earth & the sun emits EMR in much shorter wavelength .

"Solar declination is at 0 degrees" means

The sun is directly overhead at noon on the equator

The position of the earth relative to the sun effects energy in these ways

The timing, intensity, and location of incoming energy.

Stefan Boltzmann Law

The total energy emitted by an object depends on it's temperature. Hotter objects emit more energy than cooler objects. Energy = a constant X temp in K to the 4th power

Wien's Law

The wavelength emitted depends on an object's temperature. Hotter objects radiate at shorter wavelengths than cooler objects. Wavelength = constant / temp of object.

Solar declination at 23.5 degrees north =

Tropic of Cancer

The direction an axis ointment reminds consistent during a yeae

True

The sun-warmed surface of the earth transfers energy to the atmosphere WHICH CREATES

WEATHER

Radiation from the sun is measured in

Watts per meter squared (W/m2)

Perihelian

When the sun and earth are closest (January)

Aphelion

When the sun and earth are furthest apart (July)

Revolution / orbit of the earth around the sun creates

Year length 365.25 days This orbit is slightly elliptical / not truly circular

angle of incidence

Yearly changes in the position of the Earth's axis cause the location of the Sun to wander 47° across our skies. Changes in the location of the Sun have a direct effect on the intensity of solar radiation. The intensity of solar radiation is largely a function of the angle of incidence, the angle at which the Sun's rays strike the Earth's surface.

The ecliptic plane can be defined as

a two-dimensional flat surface that geometrically intersects the Earth's orbital path around the Sun. On this plane, the Earth's axis is not at right angles to this surface, but inclined at an angle of about 23.5° from the perpendicular.

An elliptical orbit of the earth around the sun produces

a year

Spectral Signature

allows science to study different surfaces of planets

Daily temperature begins rising when?

as soon as the net radiation budget of the surface becomes positive.

Variations in net radiation are primarily controlled by

changes in the intensity and duration of received solar insolation which are driven by variations in day length and angle of incidence.

The edge dividing the daylight from night is called the

circle of illumination.

The direction of Earth's rotation is

counter-clockwise if viewed from the top / north pole. Opposite from south pole.

September Equinox

exactly half the earth is in darkness and half is illuminated.

Sun is shining north of the equator means

it is sometime after march 21 and we are approaching the summer solstice

The earth emits

longwave EM radiation

The earth spins on it's axis producing

night and day

Longest days occur during the June solstice for locations ______ of the equator and on the December solstice for locations in the Southern Hemisphere.

north (northern hemisphere)

September equinox is warmer than March equinox because

of the heating that occurred in the previous summer months.

The sun warms the earth with

shortwave EM radiation

Peak reception occurs at

solar noon when the Sun attains its greatest height above the horizon

Earth's seasons are controlled by changes in the duration and intensity of

solar radiation or insolation. Both of these factors are in turn governed by the annual change in the position of the Earth's axis relative to the Sun

Temperature continues to rise until

sometime after solar noon. After this time, mixing of the Earth's surface by convection causes the surface to cool despite the positive addition of radiation and heat energy.

Incoming energy varies based on these to factors

the Earth's orientation to the sun and where on Earth it is measured

Since the Earth's axis is tilted,

the Sun is higher when you are on the part of the Earth where the axis points towards the Sun, and lower on the part of the Earth where the axis points away from the Sun.

June solstice, September equinox, December solstice, and March equinox.

the angle of the Earth's axis in relation to the ecliptic plane and the North Star on these four dates remains unchanged. Yet, the relative position of the Earth's axis to the Sun does change during this cycle. This circumstance is responsible for the annual changes in the height of the Sun above the horizon. It also causes the seasons, by controlling the intensity and duration of sunlight received by locations on the Earth.

the more energy available,

the higher up the Y-axis the profile is on the graph

Spring & Autumn

the spin axis of the Earth points 90 degrees away from the Sun. This means that on this date, day and night have about the same length: 12 hours each, more or less.

The solar energy received at any given location on Earth is dependent on

the time of day, the season, and the latitude of that location.