Pick a science word and write the definition. Chapter 20 Bell work Week 28 Pick a science word and write the definition. Chapter 20

Title of notes: Earth’s seasons Pg. 22 & 23 RS Goal for the lesson: write on self-assessment sheet I can explain why the Earth has changing seasons.

Throughout the year, as Earth orbits the Sun, many parts of the Earth experience changing seasons.

Northern Hemisphere: Part of the globe north of the equator. Southern Hemisphere: Part of the globe south of the equator. Western Hemisphere: Part of the globe west of the prime meridian. Eastern Hemisphere: Part of the globe east of the prime meridian.

Earth’s tilt This tilt causes different hemispheres to be at different angles relative to the sun at different times of the year.

How do we know the Earth is tilted? We have observed where the sun is in relation to the horizon from a specific spot on the ground at a certain time of day during an equinox, and then again during a solstice from that spot at the same time of day. We subtract the lesser result from the greater and we arrive at about 23.5°.

Solstice vs. Equinox Solstice – The point where the Earth has reached its maximum angle compared to the Sun and begins to move back in the other direction (June and December). Equinox – Earth reaches two points during the year where the tilt of its axis causes it to appear straight relative to the Sun. These days are known as equinoxes. During these equinoxes the rays of the Sun shine directly on the equator (March and September).

The seasons change depending on the amount of sunlight reaching the Earth as it revolves around the sun. Hemisphere tilted toward the sun experiences summer, the hemisphere tilted away from the sun experiences winter.

One hemisphere points toward the sun as the other points away One hemisphere points toward the sun as the other points away. The hemisphere that points toward the sun is warmer and gets more light, it's summer there, and in the other hemisphere it's winter. This effect is less dramatic near the equator than at the poles, since the equator receives about the same amount of sunlight all year. The poles, on the other hand, receive no sunlight at all during their winter months, which is part of the reason why they're frozen.

During midwinter, when a pole is tilted away from the sun, there is no daylight. During the summer, a pole receives sunlight all the time and there is no night!

Summer is warmer than winter (in each hemisphere) because the Sun's rays hit the Earth at a more direct angle . The days are much longer.

During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short.

Season simulator website! http://astro.unl.edu/naap/motion1/animations/seasons_ecliptic.html

Quick check – Pass the answer! On the index card explain why we have season changes. Trade with someone in your group. When you get a new card (someone else’s) you can change, add, or delete anything.