The Sun, Seasons and Weather

understand that energy from the Sun is the primary driver of weather on Earth. describe the revolution and tilt of Earth’s rotational account for seasons in both hemispheres Key Words Spring (vernal) equinox Fall (autumnal) equinox Latitude/Longitude Solstice Tropic of Cancer Tropic of Capricorn

At any time - half of Earth is in sunlight and half in darkness. The Earth rotates on its axis once a day. The axis is tilted at an angle of 23.5 degrees. The Earth revolves around the Sun once a year. At any time - half of Earth is in sunlight and half in darkness.

Earth rotates in an easterly direction

Insolation – because of (spherical) shape of the Earth, sun shines at different angles over different parts. Equator - sun’s energy is more direct - HOT Poles - sun’s energy is spread out over a larger area - COOL Affects the weather and climate of that part of the earth.

winter summer

When the Earth’s axis is tilted the most towards or away from the Sun’s rays. Summer Solstice – north tilted towards – June 21 Winter Solstice – north titled away – December 21

Summer Solstice – Long days, short nights.

Winter Solstice – Short days, long nights.

When Earth’ s axis is perpendicular to the Sun’s rays - exactly half of Earth is reached: Spring Equinox – about March 21 Fall Equinox – about September 23 Everywhere receives 12 hours of daylight.

SPRING/FALL

At the equator, the daily period of daylight is the same, everyday of the year. The poles have the greatest range in temperature. Sunlight variations in the Southern Hemisphere are reversed – as are the seasons. Higher latitudes (Canada) have greater variations in solar radiation received over the year, creating greater seasonal differences (Cuba).

Tropic of Cancer – most northerly location that receives direct (vertical) sunlight in summer. Arctic Circle – most northerly location reached by any sunlight in winter. Tropic of Capricorn and Antarctic Circle are the corresponding lines for the Southern hemisphere.

Longitude is measured east - west from 0o line through Greenwich, England (prime meridian). Latitude is measured north - south from the equator.