GEOG 1114 1stEdition Lecture 3 Outline of Last Lecture Physical Geography An Introduction to Earth I A Geographic Perspective II Process of Science III A portrait of the Earth 1 Solar System 2 Size and Shape 3 The Geographic Grid Outline of Current Lecture Physical Geography An Introduction to Earth III A portrait of the Earth continued 4 Earth movements 1 Seasons Summer Solstice Winter Solstice Fall Equinox Spring Equinox 2 Time Tropical year Lunar month Solar day Time zones Current Lecture Earth Movements Earth rotates on its axis once every 24 hours toward the East Earth is tilted 23 5 degrees from vertical Earth revolves around the sun in an elliptical orbit once every 365 days 5 hours 48 minutes and 46 seconds known as a tropical year The calendar year is 365 days to adjust there is the Leap year every 4 years These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Rotation has 3 Major Affects 1 Affects the flow of Air and Water Coriolis effect water and air are deflected toward the right in the northern hemisphere toward the left in the southern hemisphere the equator has little effect The Poles have a lot of Coriolis effect this is what gives us tides 2 Works with gravitational pull of the moon as we spin away from the moon the tides rise opposite of that 3 Rotation causes day and night which influences temperature humidity wind and is the big reason why humans are able to inhabit so much of the earth now Revolution is an elliptical orbit where the earth s distance from the sun is not constant One revolution takes 365 days Perihelion is when the Earth is closest to the sun on January 3rd 147 166 480 km Aphelion is when the Earth is farthest from the sun on July 4th 152 171 500 km Tilt 23 5 degrees from perpendicular Also called Earth s inclination Axis always points toward Polaris a k a the North Star Affect how much the sun hits the Earth and where on the Earth s surface the sun is hitting Because of the tilt and revolution of the earth the rays of the sun are distributed differently throughout the landscape which leads to the changing seasons If the sun hits the earth s surface from directly overhead there is more heat over a small area If the sun hits earth s surface at lower angles that energy is spread over a much larger area Seasonsare determined by tilt and revolution of the Earth and Latitudinal position There are three important conditions Declination of the sun where the latitude is receiving vertical rays solar altitude height of the sun over the horizon and the length of the day There are two solstices and two equinoxes Solstices Summer and Winter December June the sun is directly overhead at 23 5 degrees north and south Summer solstice happens around June 21 where the sun is directly above the Tropic of Cancer 23 5 degrees N The Antarctic Circle is in 24 hours of darkness Longest day of the year for our summer The North Pole is continually a circle of illumination where is gets 24 hours of sunlight Winter Solstice happens around December 21st where perpendicular rays hit the tropic of Capricorn 23 5 degrees S it leads to the opposite results as the summer solstice Equinoxes Spring and fall March September the sun is directly above the equator Fall Equinox happens around September 22 where the sun is directly overhead at the equator The days are shorter and cooler and there are equal days and nights Spring Equinox happens around March 20th where the sun is directly overhead at the equator The days begin to get longer Significance of Seasonal patterns Solar rays spread over small and large areas The tropical latitudes are consistently warmer Polar latitudes are consistently cooler There is Large seasonal variations in temperature in midlatitudes All of our resources in which we depend on in a functioning society rely on these seasonal changes Time There are three natural units of time 1 Tropical year which is marked by the return of the seasons 2 Lunar month which is marked by the return of the new moon 3 Solar day which is marked by the passage of the sun All other units such as minutes hours seconds are all man made to adjust to societal needs As civilization developed so did time telling The rise of time standardization came around with trains Time Zones Standard time A time zone 15 degrees longitude with the starting point at the Prime meridian There are 24 different time zones Daylight Savings time was originally done by Germans during WWI to conserve energy more evening sun meant less energy for lighting