http://www.angelfire.com/sc2/frankt/start_and_end_malaria.htm

Malaria SeasonMalaria Season

beginning end

http://www.dnr.state.sc.us

South Carolina Seasonality

http://hurricanes.noaa.gov/prepare/season.htm

Seasonality is caused by the tilt of the Earth relative to its orbital plane around the Sun. This causes both:

The strength of sunlight reaching the surface, and

The length of the day

to vary on a regular, yearly cycle.

http://www.doc.mmu.ac.uk/aric/eae/english.html

Observations we expect to make:

Temperature is positively correlated with the strength of sunlight reaching the surface.

Temperature is positively correlated with day length

http://www.u.arizona.edu/~korine/230/chap2_figs.htm

NOT TO SCALE!

Sun

Radiation

illuminated side

dayday

dark side

nightnight

S

NOT TO SCALE!

Sun

Radiation

axis

of r

otat

ion

axis

of r

otat

ion

equatorequator

N

NOT TO SCALE!

Sun

Radiation

Solar radiation shining more directly on Southern

Hemisphere

South - South - SummerSummer

North - North - WinterWinter

NOT TO SCALE!

Radiation

Solar radiation shining more directly on Northern

Hemisphere

http://www.secussa.nafsa.org/

North - North - SummerSummer

South - South - WinterWinter

http://www.boechat.com/tele/base/2001_11.html http://www.bbc.co.uk/science/space/solarsystem/earth/solsticescience.shtml

South: summer

North: winter

South: fall

North: spring

South: winter

North: summer

South: spring

North: fall

EquinoxEquinox – – Two specific points in the Earth’s orbit Two specific points in the Earth’s orbit when each hemisphere gets 12 hours of sunlight. when each hemisphere gets 12 hours of sunlight. Spring equinox in the Northern Hemisphere is Fall Spring equinox in the Northern Hemisphere is Fall Equinox in the Southern Hemisphere.Equinox in the Southern Hemisphere.

SolsticeSolstice – – Two specific points in the Earth’s orbit Two specific points in the Earth’s orbit when the amount of day length in one hemisphere when the amount of day length in one hemisphere has reached a maximum, and in the other has has reached a maximum, and in the other has reached a minimum. Winter solstice in the reached a minimum. Winter solstice in the Northern Hemisphere is Summer solstice in the Northern Hemisphere is Summer solstice in the Southern Hemisphere.Southern Hemisphere.

Equinox dates – September 22, March 22

Solstice dates – December 22, June 21

http://milhouse.jpl.nasa.gov/

Equinox – Two specific points in the Earth’s orbit when each hemisphere gets 12 hours of sunlight.

North Pole on March 22 South Pole on March 22

Twice a year (September 22Twice a year (September 22ndnd, March 22, March 22ndnd) every latitude on Earth ) every latitude on Earth gets exactly 12 hours of sunlight.gets exactly 12 hours of sunlight.

http://milhouse.jpl.nasa.gov/

SolsticeSolstice – Two specific points in the Earth’s orbit when the day length in one hemisphere has reached a maximum and in the other has reached a minimum.

North Pole June 21 South Pole on June 21

On the longest day of the year in the Northern Hemisphere (June 21On the longest day of the year in the Northern Hemisphere (June 21stst), ), the Sun never sets on any latitude above the Arctic the Sun never sets on any latitude above the Arctic circle circle (blue) (blue) and and latitudes below the Antarctic circle (latitudes below the Antarctic circle (redred) get no sunlight at all.) get no sunlight at all.

Subsolar latitudeSubsolar latitude – the latitude at which the Sun appears directly overhead at noon on that day.

http://www.u.arizona.edu/~korine/230/chap2_figs.htmJune 21June 21stst

Polaris appears <your latitude>

above your horizon

Rock Hill Latitude= 35oNPolaris appears 35Polaris appears 35o

above horizon to above horizon to observers in Rock Hillobservers in Rock Hill

Rock Hill Latitude= 35oN

September 22nd

35o

9090o o - 35- 35o o = 55= 55oo

35o

At midday, the Sun appears 35o down from vertical to an

observer in Rock Hill, or:

55o above the horizon.

55o

Sun directly overhead at the equator

June 21st

9090o o - 11.5- 11.5o o = 78.5= 78.5oo

At midday, the Sun appears:

78.5o above the horizon.Polaris appears <your latitude>

above your horizon

Rock Hill Latitude= 35oNPolaris appears 35Polaris appears 35o

above horizon to above horizon to observers in Rock Hillobservers in Rock Hill

Rock Hill Latitude= 35Rock Hill Latitude= 35ooNN

35o

23.5o

180180oo-145-145oo-23.5-23.5oo = 11.5 = 11.5oo

down from vertical to an observer in Rock Hill, or:145o

11.5o

78.5o

Sun directly overhead at 23.5o N

11.5o

December 22st

9090o o - 58.5- 58.5o o = 31.5= 31.5oo

At midday, the Sun appears:

31.5o above the horizon.Polaris appears <your latitude>

above your horizon

Rock Hill Latitude= 35oNPolaris appears 35Polaris appears 35o

above horizon to above horizon to observers in Rock Hillobservers in Rock Hill

Rock Hill Latitude= 35Rock Hill Latitude= 35ooNN

3535oo + 23.5 + 23.5oo = 58.5 = 58.5oo

down from vertical to an observer in Rock Hill, or:

Sun directly overhead at 23.5o S

31.531.5o o

23.523.5oo35o

58.5o

June 21st

September 22nd

December 22nd

Mid

day

Sun

Ang

le

0o

50o

40o

30o

20o

10o

60o

80o

90o

70o

31.531.5oo55.055.0oo78.5o