Seasons: Explained Standard: SPI 0607.6.6 Use a diagram that shows the positions of the earth and sun to explain the four seasons.

TNReady Question Write your answer in the top right corner of your note page.

Answer Correct answer is C.

The Earth's seasons are not caused by the differences in the distance from the Sun throughout the year.

The seasons are the result of the tilt of the Earth's axis And the Angle the sun’s rays heat the earth. The Earth's axis is tilted from perpendicular to the plane of the ecliptic by 23.45°. This tilting is what gives us the four seasons of the year. Since the axis is tilted, different parts of the globe are oriented towards the Sun at different times of the year.

Check for Understanding What two factors contribute to the Earth having seasons?

Answer The tilt of the Earth at 23.5 degrees The angle that the Sun’s radiant energy warms the Earth

Axis Tilt Deeper Explanation The tilt of the Earth at 23.5 degrees causes some places on Earth to tilt toward the Sun, while other places tilt away. When tilted toward the Sun it is summer. When tilted away it is winter. When neither tilted toward or away, it is spring or fall.

Check for understanding Where on Earth is it Summer? North or South? Where on Earth is it winter? North or South?

Answer It is summer in the southern hemisphere (tilted toward). It is winter in the northern hemisphere (tilted away).

Angle of Sun’s Rays Deeper Explanation There is the same amount of energy in every ray of sunshine that travels from the Sun to the Earth. However, the angle it hits the Earth determines how concentrated (hot) it is.

Check for Understanding Which angle would produce the warmest concentration of the Sun’s radiant energy? 40° or 70°? Which angle would produce the weakest concentration of solar energy? 25° or 60°?

Answers A 70° angle would produce the warmest concentration of the Sun’s radiant energy. A 25° angle would produce the weakest concentration of solar energy.

Summer is warmer than winter because the Sun's rays hit the Earth at a more direct angle during summer than during winter and also because the days are much longer than the nights during the summer.

Check for Understanding What kind of angle is created by the sun’s rays during the summer?

Answer A more direct angle Close to a 90 degree angle

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

Check for understanding What kind of angle is created by the sun’s rays during the winter?

Answer An extreme acute angle (small) Less than 30°

Solstices The solstices are days when the Sun reaches its farthest northern and southern declinations. The winter solstice occurs on December 21 or 22 and marks the beginning of winter (this is the shortest day of the year). The summer solstice occurs on June 21 and marks the beginning of summer (this is the longest day of the year).

Check for understanding What is the shortest day of the year called? When is it in the Northern Hemisphere? What is the longest day of the year called? When is it in the Southern Hemisphere?

Answer The shortest day of the year is called the winter solstice. In the Northern Hemisphere it is Dec 21. The longest day of the year is called the summer solstice. In the Southern Hemisphere it is Dec 21. This is usually June 21 for us in the Northern Hemisphere:)

Equinoxes are days in which day and night are of equal duration Equinoxes are days in which day and night are of equal duration. The two yearly equinoxes occur in March and September. We call them spring and fall.

So sorry that we missed the Vernal Equinox of 2018… it was Tuesday So sorry that we missed the Vernal Equinox of 2018… it was Tuesday!! March 20th The exact same amount of daylight as night time on that day.

Equinoxes The vernal equinox occurs in late March (this is the beginning of spring in the Northern Hemisphere and the beginning of fall in the Southern Hemisphere) The autumnal equinox occurs in late September (this is the beginning of fall in the Northern Hemisphere and the beginning of spring in the Southern Hemisphere).

Check for understanding What is the spring equinox called? When is it in the Northern Hemisphere? What is the fall equinox called? What does an equinox mean????

Answers The spring equinox is called the vernal equinox. In the Northern Hemisphere it occurs in March (19, 20, or 21st). The fall equinox is called the autumnal equinox. Equinox means that there are equal amounts of daylight and nighttime.

Ticket out the door Reflect on today’s lesson… Write one concept that was easy for you to understand. Write one concept that was more difficult for you to understand. Each response should be in sentence format, not just one word