# Presentation: 004100

## Advancement Training

**Earth-Sun Relationship (Unit 1-Lesson2)**

**Operations Department Training**

## Earth-Sun RelationshipIntroduction

- The Sun is a thermonuclear reactor about 93 million miles from the earth.
- The Sun is important in meteorology because all natural phenomena can be traced, directly or indirectly, to the energy received from it.

## Earth-Sun RelationshipLearning Objective

- Describe how radiation and insolation are affected by the Earth-Sun relationship.

## Earth-Sun RelationshipThe Sun

- Core temperature:  15,000,000 K
- Surface temperature:  6,000 K (10,300 F)
- The Sun radiates electromagnetic energy in all directions.  However, Earth intercepts only a small fraction of this energy.
- Most of the electromagnetic energy is in the form of light waves, with only a tiny fraction in the form of heat waves.

## Earth-Sun RelationshipSolar Composition

- *Radiation emissions consisting of gamma rays through x-rays, ultraviolet, visible and radio waves, originate in the corona.

- _[The Sun](http://www.astro.uva.nl/demo/sun/kaft.htm)_

## Earth-Sun RelationshipSolar Prominences/Filaments

- *Solar prominences/filaments are injections of gases from the chromosphere into the corona.
- *A filament appears as a long dark ribbon.
- *A prominence is a long bright ribbon.

## Earth-Sun RelationshipSunspots

- *Regions of strong localized magnetic field and indicate relatively cool areas in the photosphere.
- Appear darker than surroundings.
- *Sunspots begin as small dark areas known as pores.

## Earth-Sun RelationshipPlages

- Large irregular bright patches that surround sunspot groups.
- They are features of the lower chromosphere and often completely or partially obscure and underlying sunspot.

## Earth-Sun RelationshipFlares

- The most spectacular of the eruptive features.
- *Flares are classified according to size and brightness.
- Activity, solar winds are emitted and often intercept Earth.
- *Geomagnetic disturbances like the aurora borealis and aurora australis result primarily from the motion of electrically charged particles within the ionosphere.

## Of the nine planets in our solar system Earth is the third nearest to (or from) the Sun.
Earth varies in distance from the Sun during the year:  94 million miles in summer and 91 million miles in winter.

- Earth varies in distance from the Sun during the year:  94 million miles in summer and 91 million miles in winter.

*Earth-Sun Relationship**Earth*

## Earth-Sun RelationshipEarth

- Earth is subject to four motions in its movement through space:
- *Rotation* about its axis
- *Revolution* around the Sun
- Wobble of the axis
- Solar motion (movement of solar system with space)
- Only the above highlighted two are of any importance to meteorology.

## Earth-Sun RelationshipRotation

- Earth rotates on its axis once every 24 hours.
- One-half of Earth’s surface is therefore facing the Sun at all times.
- Rotation about Earth’s axis take place in an eastward direction. (sun rise east, set west)

## Earth-Sun Relationship Revolution

- The revolution around the Sun and the tilt of Earth on its axis are responsible for our seasons.
- Earth makes one complete revolution in approximately 365 1/4 days.
- Earth’s axis is at an angle of 23 1/2 degrees to its plane of rotation and points in a nearly fixed direction in space towards the North Star (Polaris).

## Earth-Sun RelationshipSolstices and Equinoxes

## Earth-Sun RelationshipSolstices and Equinoxes

*Earth-Sun Relationship**Solstices and Equinoxes*

- Polar Zone - Frigid Zone
- 66 1/2 N - Arctic Circle
- Temperate Zone
- 23 1/2 N - Tropic of Cancer
- Torrid Zone - Equatorial Zone - Tropical Zone
- 23 1/2 S - Tropic of Capricorn
- Temperate Zone
- 66 1/2 S - Antarctic Circle
- Polar Zone - Frigid Zone

## Earth-Sun RelationshipRadiation

- Radiation - the process by which electromagnetic energy is propagated through space.  It moves at the speed of light, which is 186,000 miles per second, and travels in straight lines in a vacuum.
- *IT IS THE MOST IMPORTANT MEANS OF HEAT TRANSFER.

## Earth-Sun RelationshipSolar Radiation

- Defined as total EM energy emitted by the Sun.
- Energy radiates from a body by wavelengths which vary inversely with the temperature of that body.
- SUN EMITS SHORTWAVE RADIATION.
- EARTH RERADIATES THE SUN’S ENERGY WITH LONGWAVE RADIATION.

## Earth-Sun RelationshipDepletion of Solar Radiation

_**Dispersion**_ - Due to the tilt of the earth, the sun’s rays hit the earth at different angles.  Rays that are not perpendicular to the earth are dispersed or spread out over a greater area.
_**Scattering**_ - solar radiation passes through the air and some of the wavelengths are deflected in all directions by molecules of gases, suspended particles, and water vapor.
_**Reflection**_ - process whereby a surface turns a portion of the incident radiation back into the medium through which the radiation came.  *Albedo is the percent of reflectivity of all wavelengths on a surface.
_**Absorption**_ - Earth and its atmosphere absorb about 64% of the insolation.  Land and water surfaces of Earth absorb 51% percent of this insolation.  The remaining 13% is directly absorbed by ozone, carbon dioxide, and water vapor.

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