Earth's Revolution and its Seasons

Transcription

1 NAME PER PART 1 - Earth's Revolution: Earth's Revolution and its Seasons Examine the Figure 1 above. Answer these questions. 1. True/False: As Earth revolves around the Sun it is always tilted toward the Sun. 2. The Labeled dates in the picture are for the [Northern, Southern] Hemisphere 3. The winter solstice occurs on what date in the Northern Hemisphere? 4. The vernal equinox occurs on what date in the Southern Hemisphere? 5. The winter solstice occurs on what date in the Southern Hemisphere? 6. Earth's rotation around the Sun is [circular, elliptical]. The sun is positioned in such a way, though slightly wrong in this diagram, to generally show Earth's distance from the sun. Interestingly Earth is closer to the Sun during the [Equinoxes; solstices] and furthest on the first day of the Northern Hemisphere [summer, winter]. 7. So, the seasons are controlled by the [tilt of the Earth; distance from the Sun] and NOT [tilt of the Earth; distance from the Sun].

2 PART 2 - The Solstices and Equinoxes Examine these Figures. The arrows refer to the source of light from the sun 1. Figure 2A shows the first day of northern hemisphere [summer, winter, spring, autumn]. Fig 2A (a) How many hours of daylight are received at the equator? (b) Latitudes north of the equator have [longer, shorter] (c) Latitudes south of the equator have [longer, shorter] (d) How many hours of daylight are received at the North Pole? (e) How many hours of daylight are received at the South Pole? 2. Figure 2B shows the first day of northern hemisphere [summer, winter, spring, autumn]. (a) How many hours of daylight are received at the equator? (b) Latitudes north of the equator have [longer, shorter] (c) Latitudes south of the equator have [longer, shorter] (d) How many hours of daylight are received at the North Pole? (e) How many hours of daylight are received at the South Pole? Fig 2B 3. Figure 2C shows the first day of northern hemisphere [summer or winter, spring or autumn]. (a) How many hours of daylight are received at the equator? (b) How many at the other latitudes? (c) However, all areas [do, do not] receive the same amount of energy from the Sun because the energy [is, is not] directly perpendicular to the surface at all latitudes. Fig 2C

3 Part 3 - Energy From the Sun. Analyze the graph below and follow the directions 1. There are three sets of data plotted below. To the right of the key, label each of the cities as either equatorial, mid-latitude, polar based on the latitude that is given. 2. Construct an annual solar radiation curve for each of the three locations. Do this by drawing smooth curved lines connecting the radiation values that are already plotted. Use three different colors. 3. Look at the quantity and units given on the Y-axis: Average Daily Radiation in "Calories per square inch per day". Calorie is a unit of [energy, force], square cm is a unit of [distance, area] and day is a unit of time. Combined they represent the total amount of radiation that Earth receives at these different latitudes; because they are real measurements of energy they take into account that not all light strikes the Earth perpendicularly because the Earth is [circular; spherical] and its axis of rotation is [vertical; tilted]. 4. According to the curves, at which latitude region shown does average daily solar radiation vary the least? [equatorial latitudes, mid-latitude, polar latitudes] 5. The variation in average daily solar radiation in #4 is primarily due to slight changes in [length of day; path of sunlight through the atmosphere] 6. The pattern of sunlight received near the equator over the course of a year indicates that the seasonal differences there are [similar to, less than] those seen for the mid-latitudes.

4 7. The graph shows that there is a 6-month period during which there is no sunlight at the [equatorial, midlatitude, polar] location. 8. According to the graph, there are months when both the mid-latitude and polar regions receive more solar radiation that the equator. The major factor that causes this to happen is the greater [length of daylight each day; height of the sun in the sky]. 9. Comparison of the three curves' indicates that the annual range (i.e., difference between minimum and maximum) [increases, decrease] as latitude increases. Now, go back to the graph and add VERTICAL LINES AT THE APPROXIMATE DATES OF THE EQUINOX ES AND SOLSTICES WITH BLACK OR GRAY COLORED PENCIL. These dates can be found in the previous parts of the activity. You should have four vertical lines. Label the intervals between the lines you just drew spring, summer, autumn, winter in the Northern Hemisphere. 10. First consider the equatorial curve. Two equal maximum points and two equal minimum points normally occur in the solar radiation curve if sky were always clear (which is never the case). This curve shows something close to this, and it is evident that the maxima occur near the [solstices, equinoxes]. 11. The area under the curves for a season can be thought of as a total solar radiation for that season. Which region has similar total radiation that is about the same for each season? [equatorial latitudes, mid-latitude, polar latitudes] 12. At the mid-latitude location, the season of and receive the most solar radiation per day. 13. At the mid-latitude location, the season of and receive the least solar radiation per day. 14. During spring and summer in the Northern Hemisphere, the south pole receives [its maximum, zero] solar radiation. In the Southern Hemisphere, these are the seasons of and.

5 Part 4 - Sun's Position in the Sky (Solar Altitude) Use the figure to the right to answer questions that follow. It shows a person (you?) standing on the ground and the Sun's position in the sky at solar noon. LABEL THE DIAGRAMS AS FOLLOWS: Fig A = Equator, Fig B = New Jersey (mid-latitude), and Fig C = North Pole 1. At the equator, the sun is directly overhead on the [equinoxes, solstices] at noon. 2. At the equator, the sun would appear in the [northern, southern] sky at noon on the first day of northern hemisphere summer. 3. At the equator, the sun would appear in the [northern, southern] sky at noon on the first day of southern hemisphere summer. 4. At the equator, the sun would appear to set exactly [due east, due west] on the first days of both spring and autumn. 5. In New Jersey, the sun is closest to directly overhead at noon on the first day of [spring, summer, autumn, winter], but it is never truly directly overhead. 6. In New Jersey, the sun is lowest in the sky on at noon of the first day of [spring, summer, autumn, winter]. 7. Imagine the Sun following the path indicated as you watched it move across the sky in New Jersey... Which date's path is the longest? Which date's path is the shortest? Which is the longest day of the year? Which is the shortest day of the year? On which dates does the Sun set due west in the horizon no matter where you are? 8. At the North Pole, what would the sun appear to do on a daily basis around the time of June 21? 9. In your own words, why is the Sun high in the sky on June 21st at the North Pole, but not the other days? 10. December 21st is not shown for the North Pole because the sun appears to circle the Earth far [above, below] the horizon.

6 Try these: Suppose you are standing at 40 N latitude on the first day of spring. How many degrees from the vertical is the sun in the sky? (Hint: it has to do with latitude and the sun's direct rays on that day). Suppose you are standing at 40 N latitude on the first day of summer. How many degrees from the vertical is the sun in the sky? (Hint: it has to do with latitude and the sun's direct rays on that day).