Part2 Lab5 Motion of the sun PDF

Preview

Summary

Solved Assignment Lab Motion of the sun...

Description

Lab – Motion of the Sun Part 1 – Intro Study the Figure below. It is drawn for someone viewing the Sun from latitude 40° N ~ Denver, CO. Remember the viewer’s latitude is the altitude of the North Star (NCP). Notice that the geometry works out so that:

the Maximum height of the Sun at the equinoxes is (90 – Latitude). Also notice that the max height of the Sun for the year happens on the Summer Solstice and adds another 23.5°.!!! ! Likewise!the!min&height!of!the!Sun!for!the!year!happens!on!the!Winter!Solstice!and!subtracts&23.5°! from!the!Equinox!height!of!the!Sun.! !

Explanation: The max. height of the Sun at the Equinox is 50° as viewed from this location. At noon on Summer Solstice the Sun will climb to a height of 50°+23.5°= 73.5°. During Winter Solstice, the highest the Sun will appear is 50° – 23.5° = 26.5°.

1

Part 2 – Seasons (Assume Northern Hemisphere.)

The seasons are caused by the tilt of the Earth’s rotation axis (23.5 degrees). This has two effects on Earth: • the!path&of&the&Sun!varies!over!the!year!(giving!longer!or!shorter!amounts!of!daylight)!and!! • the!sun&angle!(giving!more!direct!or!concentrated!sunlight!when!the!angle!between!the!Sun’s!rays! and!the!horizon!is!largest)!

Mar 20

June 21

Sept 23

Dec 21

1.

What!date!has!the!longest!hours!of!daylight?!___________________!

2.

What!is!the!name!for!this!date?!(in!the!previous!question)!___________________!!!________________________!

3.

What!date!has!the!longest!hours!of!night?!___________________!

4.

What!is!the!name!for!this!date?!(in!the!previous!question)!___________________!!!________________________!

5.

What!dates!have!equal!hours!of!daylight/night?!___________________and!________________!

6.

What!are!the!names!of!these!dates?!___________!!______________!!and!!!____________!!_____________!

7. The!figure!below!is!a!180°!panoramic!view!to!the!south!showing!the!daytime!path!of!the!Sun!at!four! different!times!of!the!year!at!some!middle!northern!latitude.!!At!this!latitude,!the!top!path!is!as!high!in!the! sky!as!the!Sun!gets,!while!the!lowest!path!is!as!low!as!it!gets.!!For!the!middle!path,!the!Sun!rises!exactly!in! the!east!and!sets!in!the!west.!!Using!the!letter!given!in!the!Figure,&fill&in&the&blanks&below.& ! ! Summer Solstice_______, Winter Solstice ______, Autumnal equinox____, Vernal Equinox____, Longest day_____, Shortest day _____, day and night equal _____ angle b/tw Sun’s rays an horizon largest______, angle b/tw Sun’s rays and horizon smallest_____

Figure 1 - Paths of the Sun, Facing due South

2

Suppose the spin axis and the Earth’s orbital axis were perpendicular; that is the 23.5° angle is reduced to 0°. Your location on Earth is given by a white dot in the month D. 8.

At!which!of!the!four!months,!if!any,!would!day!be!longest!compared!to!night?!________!

9.

At!noon,!on!which!of!the!four!months,!if!any,!would!sunlight!strike!the!surface!of!the!Earth!where!you! live!at!the!largest!angle?!_______!

10. What!kind!of!seasons!would!you!experience?!___________________________________________! 11. Which!planet/s!in!our!Solar!System!closely!models!this!situation?!_______________________! Name of Planet

Axial Tilt in Degrees

Mercury ~ 0°

Mars

Venus

177.36°

Jupiter 3.13°

Earth

23.5°

Saturn

25.19°

Uranus

97.77°

Neptune

28.32°

26.73°

Suppose the spin axis and the Earth’s orbital axis were perpendicular; that is the 23.5° angle is increased to 90°. Your location on Earth is given by a white dot in the month D. 12. At!which!of!the!four!months!would!day!be!longest!compared!with!the!night?!_________! 13. At!which!of!the!four!months!would!you!experience!equal!day!and!night!times?!_______! 14. What!kind!of!seasons!would!you!experience?!___________________________________________! 15. Which!planet!in!our!Solar!System!closely!models!this!situation?!_____________!

3

Part 3 – The Flagpole’s Shadow

Big Question - Imagine an upright flagpole. From your current location, will there be any days of the year that the Sun will cast no shadow because the Sun is directly overhead? 16. Use!Fig.!1.!!! Max Altitude of Sun at Equinoxes__________° Altitude of NCP _________° Where!I!am…!!Latitude!=!!__________°!N!!! ! Are!there!days!when!Sun’s!rays!will!cast!no! shadow?! !(Y!or!N)!!If!yes,!then!write!dates.!

Figure 1- Path of the Sun

17. Use!Fig.!2.!!! Max Altitude of Sun at Equinoxes__________° Altitude!of!NCP!_________°! Where!I!am…!Latitude!=!!__________°!N!!! ! Are!there!days!when!Sun’s!rays!will!cast!no!shadow?! (Y!or!N)!!If!yes,!then!write!dates.!

Figure 2 - Path of the Sun

4

18. Use!Fig!3.!! Max Alt of Sun at Equinoxes__________° Altitude of NCP _____________° Where I am … Latitude = __________° N ! Are!there!days!when!Sun’s!rays! will!cast!no!shadow!because!it!is! directly!overhead?! (Y!or!N)!!If!yes,!then!write!dates.! ! ! ! ! ! !

Figure 3- Path of the Sun

19. Use!Fig!4.!! Max Altitude of Sun at Equinoxes__________° !Altitude!of!NCP!_____________°! Where!I!am…!!Latitude!=!!__________°!N!!! ! Are!there!days!when!Sun’s!rays!will! cast!no!!!!!!!!!shadow?!! (Y!or!N)!!If!yes,!then!write!dates.!

Figure 4- Path of the Sun

! 20. As!seen!from!St.!Cloud,!MN,!when!will! an!upright!flagpole!cast!no!shadow!because!the!Sun!is!directly!above!the!flagpole?! a. Every!day!at!noon! b. Only!on!the!first!day!of!summer! c. Only!on!the!first!day!of!winter! d. On!both!the!first!days!of!spring!and!fall! e. Never!

5

21. On!or!about!March!20!the!Sun!will!rise!exactly!in!the!east.!!Two!weeks!later!what!direction!will!the! Sun!rise?! a. The!same!place! b. Further!south! c. Further!north! d. Further!west! 22. On!or!about!Sept!23!the!Sun!will!rise!exactly!in!the!east.!!Two!weeks!later!what!direction!will!the!Sun! rise?! a. The!same!place! b. Further!south! c. Further!north! d. Further!west! 23. In!the!Northern!Hemisphere!in!order!to!have!at!least!one!day!of!the!year!that!the!Sun!will!be!directly! overhead,!you!will!need!to!be!at!latitude!________!or!lower.!!There!is!a!special!name!for!this!latitude;!it! is!called!the!Tropic'of'Cancer.!!(Hint:!!!Review!Q.19)! a. 66.5!degrees! b. 23.5!degrees! c. 15!degrees! d. 75!degrees!

**** End of Lab ***

6...