6(h). Earth-Sun Geometry
May 7, The term Earth rotation refers to the spinning of our planet on its axis. Yet, this phenomenon is not responsible for the Earth's seasons! . The annual change in the relative position of the Earth's axis in relationship to the Sun causes the . All answers from this equation are given relative to True North for. The answer may surprise you. Many people believe that Earth is closer to the sun in the summer and that is why it is hotter. And, likewise, they think There is a different reason for Earth's seasons. Earth's View of Earth in relation to sun. Not considering tropical areas, what is the general relationship between latitude, There is still an expectation that your answer will match up to a certain changes from year to year, but you should also recognize a long-term pattern in the that the changing distance from the Earth to the Sun is not the cause of seasons.
If you are earth, as you orbited the sun, were you always in the same relation to the sun? Clearly, the answer is no, but if students did not recognize this, have one pair do the exercise again.
Have the "earth" student stop at various places and ask if she is facing the sun the same way. This exercise should help students visualize that the axis is always pointed in the same direction.
Lab 1: Solar Radiation & Seasons
For instance, it is important for students to understand that the Northern Hemisphere "leans" toward the sun during part of the year resulting in more intense sunlight in that area of earth. During another part of the year it leans away, resulting in less intense sunlight and cooler weather.Earth-Sun Relationship
The next exercise will demonstrate visually the "tilt" of earth and how different areas receive more intense sunlight throughout the year. Put a large ball on a desk. Hold up an apple, stem facing up, and draw the equator with a marker explaining as you go along.
Now poke a pencil all the way through the apple from top to bottom and explain that the top where the stem comes out is in the area of the Northern Hemisphere. If the earth is tilted on its axis how should I tilt the earth apple?
Now, with your earth apple tilted properly, be sure to keep the pencil pointed in the same direction as you start to walk it orbit around the bigger ball sun. It is easiest to keep the pencil facing toward the same wall. Do one full orbit, then do another orbit and stop at when the Northern Hemisphere is leaning toward the sun. Where is the Northern Hemisphere pointed? It is pointed toward the sun.
The Four Seasons - Science NetLinks
Do you think the Northern Hemisphere is warmer during this time of the year? Yes, because sunlight is hitting it directly. Now, keep orbiting until the Northern Hemisphere is pointed away from the sun and ask: When the Northern Hemisphere points away from the sun, then what? Now, the Northern Hemisphere gets cooler.
The Four Seasons
Why does the Northern Hemisphere get cooler? Again it is important for them to realize that it is the sunlight falling less intensely that causes it to be cooler. The average distance of the Earth from the Sun over a one-year period is about Position of the equinoxes, solstices, aphelion, and perihelion relative to the Earth's orbit around the Sun.
Tilt of the Earth's Axis Figure 6h Seasons are appropriate only for the Northern Hemisphere. Annual change in the position of the Earth in its revolution around the Sun. In this graphic, we are viewing the Earth from a position in space that is above the North Pole yellow dot at the summer solstice, the winter solstice, and the two equinoxes.
Note how the position of the North Pole on the Earth's surface does not change. However, its position relative to the Sun does change and this shift is responsible for the seasons. The red circle on each of the Earths represents the Arctic Circle During the June solstice, the area above the Arctic Circle is experiencing 24 hours of daylight because the North Pole is tilted Click Equinoxes to open the file in Microsoft Excel.
For all seven locations, you will be examining the noon altitude of the Sun i. The higher the noon altitude of the Sun the more intense the solar radiation. You are going to convert that data into a bar chart within Excel using the following steps: The resulting chart shows the noon altitude of the Sun on March 20 and September 22 at the seven latitudes i. Feel free to make the graph large and change its shape.
Where was the noon altitude of the Sun highest and lowest on the equinoxes? Make a bar chart with the data in the Daylight Hours worksheet tab.
Look at the tabs on the bottom of Excel. Approximately how many hours of daylight did each of the locations receive on the two equinoxes? As you just discovered, during the two equinoxes per year, the Sun is directly overhead the equator and all places on Earth receive approximately 12 hours of sunlight.
For all seven latitudes, you will be examining the noon altitude of the Sun i. Make a bar chart with the data in the Noon Altitude of the Sun worksheet tab.
What locations had the most and fewest daylight hours on June 21? What locations had the most and fewest daylight hours on December 21? As you just discovered, during the June Solstice the Sun is directly overhead the Tropic of Cancer During solstices, there are extremely large differences in solar intensity and daylight hours between the northern and southern hemispheres.
The above difference in sunlight found among latitudes exist along all lines of longitude e. We are going to use the lamps to compare the intensity of noon sunlight at Lake Nasser On which date, June 21 or December 21, should Lake Nasser receive more intense solar radiation?
Earth-Sun Relations and Seasons
We are assuming there are no clouds or other things that can absorb, reflect, or scatter solar radiation. Below are screenshots from the Seasons and Ecliptic Simulator you explored earlier.
The large panel and the top-right panel show which hemisphere is tilted towards the Sun.