The Reasons for Seasons Copyright 2005 by the Rector and Visitors of the University of Virginia 2/24/2019 The Seasons
Rotation vs. Revolution Rotation is the spin of an object about its axis. The Earth rotates once a day (once every 24 hours). Revolution is the orbit of one object around another. The Earth revolves around the Sun every 365.26 days. 2/24/2019 The Seasons
Tilt of the Earth’s Axis The axis around which the Earth rotates is tilted by 23.5 degrees. 2/24/2019 The Seasons
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Do this… Complete 1-4: Checking Concepts on Page 327. Complete 5-8: Thinking Critically on the Same page. 2/24/2019 The Seasons
Time Zones The Continental U.S. has four time zones. Eastern Standard Central standard Mountain standard Pacific Standard 2/24/2019 The Seasons
Time Zones 2/24/2019 The Seasons
Solar Noon: time of day when the sun is highest in the sky. Time Zones Solar Noon: time of day when the sun is highest in the sky. 2/24/2019 The Seasons
International Date Line The International Date Line line was established in the middle of the Pacific Ocean. As you go from east to west, you gain a day as you cross the line. As you go from west to east, you lose a day as you cross the line. 2/24/2019 The Seasons
Daylight Saving Time During the late spring, and early fall, we set our clocks ahead/back to gain or lose an hour. This change in time is called Daylight Saving Time. spring ahead, fall back. 2/24/2019 The Seasons
Do This: Complete Checking concepts: 1-5 and Thinking Critically: 6 – 10. 2/24/2019 The Seasons
Equinoxes and Solstices The Vernal (Spring) Equinox (about March 21): When night and day are the same length. The Summer Solstice (about June 21): The location where the Sun is at its highest in the sky. Longest day of the year. 2/24/2019 The Seasons
Equinoxes and Solstices The Autumnal (Fall) Equinox (about September 21): When day and night are the same length. The Winter Solstice (about December 21): The location where the Sun is at its lowest point in the sky. Shortest Day of year. 2/24/2019 The Seasons
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Tropics 2/24/2019 The Seasons
Seasons Misconception Perihelion when earth is at its closest point to the sun. Aphelion when earth is at it farthest point from the sun. 2/24/2019 The Seasons
Seasons Misconception While it is winter in the Northern hemisphere it is summer in the Southern hemisphere. If the seasons were due to our distance from the Sun both hemispheres would have the same seasons at the same time. 2/24/2019 The Seasons
Orbit of the Earth 2/24/2019 The Seasons
The Length of the Day A day is defined as the time that it takes the Earth to rotate on its axis. Duh! 2/24/2019 The Seasons
Length of a Year It takes Earth one year to orbit the Sun That’s 365.26 days to you. Duh! A sidereal year is the length of time it takes for the Earth to return to the same position 2/24/2019 The Seasons