OUR IMPORTANT INFLUENCERS

FOR YOUR NOTEBOOK:

Lesson 4:  Our Important Influencers

The Seasons

• Earth’s axis is tilted at 23.5 degrees and this axis tilt remains fixed causing the cycle of the seasons

  • During winter in the northern hemisphere, sunlight strikes the north pole at an angle that spreads the sun's energy for a short period of time.  Less concentrated radiation leads to lower heat energy absorption.

  • The angle also gives us shorter days which contributes to lower temperatures

    • This timing is referred to as a solstice

    • Summer solstice- June 21 Longest Day; Winter solstice- December 21 Shortest Day

  • During spring in the northern hemisphere, the days and nights are relatively equal due to Earth’s axis being perpendicular to the Sun’s rays

    • This timing is referred to as an equinox

    • Vernal equinox- around March 20; Autumnal equinox- around September 22

  • During summer in the northern hemisphere, sunlight strikes the north pole more directly for a longer period of time (=long days, warmer temperatures)

• The tilt of the Earth’s axis means that the seasons in the northern hemisphere are opposite those in the southern hemisphere (Summer in the northern hemisphere and winter in the southern hemisphere)

Solar Eclipses

• When the moon casts a shadow on Earth as it passes between the Sun and Earth

  • Umbra- the inner, cone-shaped portion, which blocks direct sunlight (total solar eclipse)

    • The umbral shadow is never wider than 270 km, so those who will see a total solar eclipse are in a very small path (Path of Totality)

  • Penumbra- the outer portion of the shadow, where some sunlight reaches (partial solar eclipse)

  • Annular eclipse- the moon appears too small to fully cover the sun because it is at apogee, leaving a ring (annulus) of light around the edge of the moon

    • Apogee- the farthest point in the Moon’s orbit to Earth

    • Perigee- the closest point in the Moon’s orbit to Earth​