Earth-Sun Relationship Geography: Chapter 3, Lesson 1

Climate and Weather What is the difference between climate and weather? Weather is the condition of the atmosphere in one place over a short period of time, such as hours or days When you look outside and decide what to wear that day, you are checking the weather Climate refers to the average weather conditions as measured over many years You might decide what house you want to buy based on the climate, not on that day’s weather

While a weather report gives you the weather for the day and predicts up to 10 days ahead, a climate map includes years of data to figure out what a place is like overall

Earth’s Tilt and Rotation The Earth’s axis, which runs from the north to the south pole, is tilted at about 23½ degrees, similar to how the globe in this room is tilted Because the Earth is tilted, not all places on the Earth receive the same amount of sunlight at the same time The part of the Earth that is tilted away from the sun is having winter; the part of the Earth that is tilted toward the sun is having summer That is why the Northern Hemisphere has summer from June until September while the Southern Hemisphere has winter during those same months

Earth’s Revolution The relationship between the Earth and the sun directly affects climate The Earth both rotates and revolves The Earth’s rotation is 24 hours as it spins on its axis, making one day Since the Earth rotates like a rotisserie chicken, an equal amount of heat gets spread evenly over the Earth, rather than just one side getting burned The Earth revolves around the sun, completing its journey in 365¼ days, which is how we got the idea of one year https://youtube.com/watch?v=0jHsq36_NTU The helical model - our solar system is a vortex

Equinox and Solstice Twice a year, on March 21st and September 23rd, the sun directly hits the equator These dates are called equinox (equal night), because daytime and nighttime are each 12 hours long During equinox, equal amounts of light hit both the Northern and Southern Hemisphere for the only time during the year. It is the transition between the seasons of winter/ spring and summer/ fall In addition to the equator, which runs directly around the middle of the Earth, there are two other important lines of latitude: the Tropic of Cancer (23½ degrees north) and the Tropic of Capricorn (23½ degrees south) These are the furthest north and south that the sun hits– the sun is directly overhead– on June 21st and December 22nd, the beginnings of summer and winter for both hemispheres (in South America, January means it is summertime) On those dates, it is sunny at midnight at one pole, while remaining dark all day at the other pole Alaska and the Scandinavian countries have midnight sun celebrations in the summer

The Greenhouse Effect Most of the sun’s rays toward the earth are immediately reflected back by the atmosphere. This keeps us from overheating On the other hand, the atmosphere also acts as a jacket around the Earth, keeping the right amount of heat in The insulation from the atmosphere is known as the greenhouse effect, trapping heat as a greenhouse traps heat for plants Without this greenhouse effect, the Earth’s average temperature would be about zero degrees Fahrenheit, with extreme hot and cold spells, and life could not exist in those conditions

Homework In your journal, complete #1-5 from page 63 in your text