Earth’s Seasons & Climate Zones: An In-depth Guide

Posted on Oct 13, 2024 in Chemistry

Module 3: Seasons

Earth’s Axis and Movement

1. What is the Earth’s axis?
It is an imaginary straight line passing through the Earth’s center. The Earth rotates around this line. The points where this line intersects the Earth’s surface are the North and South Poles.

2. What are the movements of Earth’s axis called?

• Precession
• Nutation

3. What is the Equator?
It is the great circle perpendicular to the Earth’s axis that divides the Earth into two hemispheres: the Northern Hemisphere (or Boreal) and the Southern Hemisphere (or Austral).

4. What are parallels?
They are smaller circles parallel to the Equator. Their length decreases as they approach the poles.

5. What are meridians?
They are circles passing through the poles.

6. What are geographic coordinates?
They are numbers that allow us to locate any point on the Earth’s surface.

7. Which are the geographic coordinates?

• Latitude
• Longitude

8. What is latitude?
It is the distance from a point on the Earth’s surface to the Equator. It is measured in degrees of meridian.

• A point above the Equator: North Latitude
• A point below the Equator: South Latitude

9. What is longitude?
It is the distance from a point on the Earth’s surface to the Prime Meridian. It is measured in degrees of the Equator.

• A point to the right of the Prime Meridian: East Longitude
• A point to the left of the Prime Meridian: West Longitude

10. What are the approximate latitude and longitude of Logroño?
42° 30′ N, 2° 30′ W

11. What is the latitude of the Equator?
0°

12. What is the latitude of the poles?
90° N and 90° S

13. What is the Prime Meridian?
The meridian of 0° longitude.

Earth’s Rotation and Speed

14. What is the direction of Earth’s rotation?
West to East

15. What is the rotational speed at a point on the Equator?
1,666 km/h

16. What is Earth’s orbital speed?
30 km/s

17. Express 1,666 km/h in km/s.
0.46 km/s

18. Express 30 km/s in km/h.
108,000 km/h

Tropics, Polar Circles, and Seasons

19. What are the Tropics?
Two parallels 23° 27′ away from the Equator.

• Northern Hemisphere: Tropic of Cancer
• Southern Hemisphere: Tropic of Capricorn

20. What are the Polar Circles?
Two parallels 23° 27′ away from the poles.

• Northern Hemisphere: Arctic Circle
• Southern Hemisphere: Antarctic Circle

21. What are the equinoxes?
Two seasons (Spring and Autumn) with equal daylight and darkness hours (12 hours each).

22. When do the equinoxes occur?
Spring Equinox: March 20-21
Autumn Equinox: September 22-23

23. What are the solstices?
Two seasons (Summer and Winter) with the greatest inequality between daylight and darkness hours.

• Summer: Longest day, sun over the Tropic of Cancer
• Winter: Shortest day, sun over the Tropic of Capricorn

24. When do the solstices occur?
Summer Solstice: June 21-22
Winter Solstice: December 21-22

25. What is the ecliptic?
The elliptical path of the Earth around the Sun.

26. What is an ellipse?
A closed curved line where the sum of the distances from any point on the curve to two fixed points (foci) is constant.

27. What does the angle of 23° 27′ represent?
The angle between the Earth’s equatorial plane and the ecliptic plane.

Climate Zones

28. What are the Earth’s climate zones?

1. Torrid Zone
2. North Temperate Zone
3. South Temperate Zone
4. Arctic Zone
5. Antarctic Zone

29. Define the boundaries of Earth’s climate zones.

1. Torrid Zone: Between the Tropic of Cancer and the Tropic of Capricorn
2. North Temperate Zone: Between the Arctic Circle and the Tropic of Cancer
3. South Temperate Zone: Between the Antarctic Circle and the Tropic of Capricorn
4. Arctic Zone: Between the Arctic Circle and the North Pole
5. Antarctic Zone: Between the Antarctic Circle and the South Pole

30. Determine the latitudes of the polar circles mathematically.
Arctic Circle: 66° 33′ N
Antarctic Circle: 66° 33′ S

31. What is the angular width of each temperate zone?
43° 6′

Perihelion, Aphelion, Perigee, and Apogee

32. What is perihelion?
The point in a planet’s orbit where it is closest to the Sun.

33. What is aphelion?
The point in a planet’s orbit where it is farthest from the Sun.

34. What is perigee?
The point in the orbit of a celestial body where it is closest to the Earth.

35. What is apogee?
The point in the orbit of a celestial body where it is farthest from the Earth.

36. What is the relationship between Earth’s perihelion and the Sun’s perigee? What is the relationship between Earth’s aphelion and the Sun’s apogee?
In both cases, the distance between the Earth and the Sun is the same.

Speed of Light and Astronomical Units

37. If light travels 3,000 km in one-hundredth of a second, what is its speed?
300,000 km/s

38. What is the exact value of the speed of light in km/s? What symbol represents it?
299,792.5 km/s. Represented by ‘c’.

39. How long does it take for sunlight to reach Earth (average distance of 150 million km)?
8 minutes and 20 seconds

40. What is a light-year?
The distance light travels in one year.

41. What is an astronomical unit (AU)?
The average distance between the Earth and the Sun (150 million km).

42. What is a parsec (pc)?
3.26 light-years. It is the distance at which 1 AU subtends an angle of 1 arcsecond.

43. The planet Sedna is about 13 billion kilometers from the Sun. How much is this distance in AU?
87 AU

44. Calculate the distance to Vega (Alpha Lyra) in light-years, given its distance is 257.5 × 10¹² km. (1 year = 31,556,926 seconds; c = 299,792 km/s)
27.2 light-years

Eons and the Age of the Sun

45. What is an eon?
One billion years (1,000,000,000 years).

46. What is the age of the Sun?
5 eons (5 billion years).

47. Summary table of the seasons.
(Photocopy A)

Factors Affecting Seasons

48. What three factors account for the heat of summer and the cold of winter?

1. Earth-Sun distance
2. Length of the day
3. Angle of sunlight (inclination)

49. Which of these three factors has the greatest influence?
The angle of sunlight.

50. How does the Earth-Sun distance affect summer heat and winter cold? What common misconception should be avoided?
The closer the Earth is to the Sun, the warmer it is. The farther away, the colder it is.
Avoid saying that summer is caused by the Earth being closer to the Sun, and winter is caused by the Earth being farther away.

Earth’s Motions and Consequences

51. Summarize Earth’s motions and their consequences.

52. What would happen if the Earth’s axis were not tilted?
There would be no seasons; it would be a constant spring/summer.

53. The Book of Enoch states that a year has 364 days. Discuss this.
It is possible that when Enoch lived, a year was 364 days long. Perhaps the Sun had more mass, resulting in a stronger gravitational pull on Earth. This would mean Earth was closer to the Sun and its orbit was shorter.

54. How does the length of the day affect summer heat and winter cold?
More daylight hours mean more solar energy, leading to higher temperatures. However, the angle of sunlight is also crucial. Consider the poles, which have 6 months of daylight and 6 months of darkness.

55. Describe solar lighting near the poles.
In summer, the Sun is high in the sky, and solar radiation is more direct and concentrated. In winter, the Sun’s rays are very oblique.

56. How does the direction (or angle) of sunlight affect summer heat and winter cold?
Due to Earth’s axial tilt, each pole receives sunlight for about 6 months while the other is in darkness. This reverses every 6 months.

57. Suggest simple experiments to demonstrate the influence of the three factors on seasonal temperatures.
Use a candle:

• Hold your hand at different distances from the flame to feel the heat (distance).
• Hold your hand for a minute, then remove it to observe the heat effect (duration).
• Hold your hand at different angles to the flame (tilt).

Eratosthenes of Cyrene

58. What are some facts about Eratosthenes of Cyrene?

• Astronomer
• Student of Archimedes
• Known as β (Beta)
• Developed the Sieve of Eratosthenes (for finding prime numbers)
• Director of the Library of Alexandria
• Calculated Earth’s circumference using a stick
• Geographer, historian, and writer
• Died at age 80 (around 300 BC), blind, by voluntarily stopping eating

Module 4: Physical and Chemical Phenomena (I)

Bunsen Burner Characteristics

Separating Salt and Sand

1. List the utensils needed to separate salt and sand.

• Spoon/Spatula
• Mortar and Pestle
• Test Tube
• 250 ml Beaker
• Glass Rod
• Funnel
• Erlenmeyer Flask
• Evaporating Dish
• Ring Stand
• Ring Stand Clamp
• Wire Gauze
• Asbestos Pad
• Bunsen Burner

2. Describe the procedure for separating salt and sand.

1. Mix two tablespoons of salt and two of sand in a mortar and pestle.
2. Add the mixture to a test tube with 60 ml of water.
3. Dissolve as much of the mixture as possible.
4. Filter the mixture through filter paper in a funnel, collecting the filtrate in the Erlenmeyer flask. The sand will remain on the filter paper.
5. Allow the sand to dry.
6. Pour the salt solution into the evaporating dish.
7. Heat the evaporating dish on a wire gauze over a Bunsen burner until the water evaporates, leaving the salt behind.

3. What is meant by “loss of salt by crackling” during this process?
If the salt is heated without water, it will start to jump out of the evaporating dish, making a crackling sound.

4. How do you prepare filter paper for use in a funnel?

1. Moisten the filter paper with a few drops of water.
2. Press it against the sides of the funnel to create a cone shape.

5. Lab Accident #1 (Drawing): Identify safety hazards.
The drawing depicts numerous safety hazards, including loose hair, handling electrical plugs with wet hands, spills, improper storage of chemicals, incorrect heating techniques, cluttered workspaces, and unattended experiments.

6. Lab Accident #2 (Drawing): Identify safety hazards.
Similar to the previous drawing, this one shows unsafe practices such as dirty workspaces, handling electrical equipment with wet hands, conducting experiments on unstable surfaces, flammable materials near heat sources, improper handling of chemicals, and a general lack of attention to safety protocols.

Crystallization of Copper Sulfate

7. What is the formula for copper sulfate pentahydrate?
CuSO₄ · 5H₂O

8. What is the shape of copper sulfate pentahydrate crystals?
Rhomboid

9. What is an important use of CuSO₄?
Fungicide in agriculture

10. List the materials needed for the crystallization of copper sulfate.

• Spoon/Spatula
• Mortar and Pestle
• 600 ml Beaker
• Glass Rod
• Thermometer
• Funnel
• Crystallizing Dish
• 2 Ring Stands
• 2 Ring Stand Clamps
• 3 Nuts
• 2 Wire Gauzes
• Asbestos Pad
• Bunsen Burner

11. Describe the procedure for crystallizing copper sulfate.

1. Grind copper sulfate in a mortar and pestle.
2. Heat 500 ml of water in a beaker to boiling.
3. Add the copper sulfate to the boiling water.
4. Continue heating until the solution turns deep blue and reaches 75°C.
5. Filter the solution.
6. Pour the filtrate into the crystallizing dish and let it stand for 2-3 weeks.

12. What is the visual difference between hydrated and anhydrous copper sulfate?
Anhydrous copper sulfate is white. Hydrated copper sulfate (CuSO₄ · 5H₂O) is blue.

13. What is a hydrate?
A solid compound containing water molecules within its crystal structure.

14. Give two examples of hydrates and their names.

• CuSO₄ · 5H₂O: Copper sulfate pentahydrate
• FeCl₃ · 6H₂O: Iron(III) chloride hexahydrate

31. What is Mitscherlich’s Law?
Isomorphous compounds have similar chemical compositions.

32. What is isomorphism?
Different chemical substances with similar structures can crystallize in the same form, with similar interfacial angles and axial ratios.

Physical and Chemical Phenomena (II)

Glass

1. Why is glass not described as a solid?
Glass does not have a sharp melting point. It softens and becomes plastic when heated, behaving like a viscous liquid.

2. What is the key to working with glass successfully?
Heating it sufficiently.

3. What precaution should be taken when handling hot glass?
Hot glass looks the same as cold glass, so be careful not to burn yourself.

4. How do you cut a glass tube with a triangular file?
Place the tube on the table and hold it firmly. Make a single, transverse notch with the file. Do not score the tube completely around its circumference.

5. How should the file be used when making a notch in a glass tube?
Use a single, firm stroke in one direction. Do not use a sawing motion, as this may shatter the glass.

6. How and where should you place your hands to break a glass tube after making a notch? (Include a drawing).
Place your thumbs on opposite sides of the tube, directly opposite the notch. Grip the tube firmly with your fingers.

7. In what direction should force be applied to break a glass tube? (Include a drawing).
Apply force outwards, as if bending the tube away from the notch.

8. What should you do if moderate force does not break the tube?
Deepen the notch with the file, rather than applying excessive force.

9. Summarize the process of cutting a glass tube.
Steps 4 through 8 describe the process.

10. What is fire polishing?
Heating the cut end of a glass tube to smooth and round it.

11. Why should heat be applied carefully during fire polishing?
To avoid closing or deforming the opening of the tube.

12. Why is fire polishing necessary?

• To prevent cuts.
• To prevent rubber stoppers from tearing when inserted into the tube.

13. When heating a glass tube for bending or fire polishing, how should the tube be handled?
Rotate the tube continuously to ensure even heating.

14. How do you bend a glass tube?
Heat a 3 cm section of the tube evenly. Gently bend the ends to the desired angle.

15. What indicates that the glass is hot enough to bend?

• The flame turns yellow.
• The tube begins to sag.

16. How do you stretch a glass tube?
Heat a 3 cm section evenly. Gently pull the ends apart until the heated area becomes narrow and elongated, forming a dropper or capillary.

Determining Melting Point

17. What is a chemical formula?
A way of representing the composition of a substance.

18. What is the condensed formula of p-dichlorobenzene?
C₆H₄Cl₂. A condensed formula indicates the composition of a substance.

19. Why is p-dichlorobenzene also called 1,4-dichlorobenzene? Explain using a structural formula.
The structural formula shows the arrangement of atoms, indicating the chlorine atoms are attached to the 1st and 4th carbon atoms in the benzene ring.

20. What are the properties of p-dichlorobenzene?

• White solid
• Used as an insecticide

21. Why doesn’t it matter if the p-dichlorobenzene isn’t fully submerged in water when determining its melting point?
Because p-dichlorobenzene does not dissolve in water.

22. What melting point was obtained for p-dichlorobenzene in your group’s experiment?
62°C

Reaction of Hydrochloric Acid with Ammonia

23. Explain the principle of communicating vessels.
When two containers are connected, liquid will flow between them until it reaches the same level in both, regardless of their shape.

24. How were pipettes used in the reaction of hydrochloric acid with ammonia?
Different colored pipettes were used for each substance.

25. How were samples of hydrochloric acid and ammonia obtained safely?
HCl: Test tube
NH₃: Pipette
Clearly label each container.

26. Write the chemical equation for the reaction between hydrochloric acid (HCl) and ammonia (NH₃) to produce ammonium chloride (NH₄Cl).
HCl + NH₃ → NH₄Cl

27. Calculate the molecular weights of HCl, NH₃, and NH₄Cl, given the atomic weights of H=1, Cl=35.5, and N=14.
HCl: 1 + 35.5 = 36.5 g/mol
NH₃: 14 + (3 × 1) = 17 g/mol
NH₄Cl: 14 + (4 × 1) + 35.5 = 53.5 g/mol

28. How do you calculate the molecular weight of a substance?
Sum the atomic weights of all the atoms in the molecule.

29. What is a mole (or gram molecule) of a substance? How many grams are in a mole of HCl, NH₃, and NH₄Cl?
A mole is the molecular weight of a substance expressed in grams.
HCl: 36.5 g
NH₃: 17 g
NH₄Cl: 53.5 g

30. Define a mole (or gram molecule).
The molecular weight of a substance expressed in grams.

32. What is the stoichiometry of the reaction between HCl and NH₃?
36.5 g of HCl reacts with 17 g of NH₃ to produce 53.5 g of NH₄Cl.

33. Why is the white ring of ammonium chloride closer to the HCl-impregnated paper in the reaction between HCl and NH₃?
HCl molecules are heavier and diffuse more slowly than NH₃ molecules.

34. Ammonia molecules move faster than HCl molecules. How much faster? How do you determine the ratio V_Ammonia/V_HCl?
The ratio of their speeds is inversely proportional to the square root of the ratio of their molecular weights.

35. Discuss the mathematical calculations performed in the reaction of HCl with NH₃.
(Calculations from previous years)

Reaction of Hydrochloric Acid with Various Metals

36. What is the effect of adding water to test tubes containing metals and hydrochloric acid?
Dilutes the acid, reducing the reaction rate and producing hydrogen gas bubbles.

37. Which metals reacted with HCl in the experiment?

• Zinc (Zn)
• Aluminum (Al)
• Iron (Fe)

38. Write the chemical equations for the reactions of these metals with HCl.
Zn + 2HCl → ZnCl₂ + H₂
2Al + 6HCl → 2AlCl₃ + 3H₂
Fe + 2HCl → FeCl₂ + H₂

39. Which metals did not react with HCl?

• Lead (Pb)
• Copper (Cu)

40. What are exothermic reactions?
Reactions that release heat.

41. Which reactions of HCl with metals are exothermic?
The reactions with Zn, Al, and Fe.

Hydrochloric Acid

48. What is the relationship between hydrochloric acid and hydrogen chloride?
Hydrochloric acid is an aqueous solution of hydrogen chloride (HCl).