1. Earth-Sun Relationship
Geography: Chapter 3, Lesson 1

2. 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

3. 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

4. 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

6. 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
The helical model - our solar system is a vortex

7. 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

9. 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

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