External Controls

Question 1

what does it mean by solar variability

Answer 1

how many sunspots present

Question 2

define sunspot

Answer 2

dark areas on suns surface which are central parts of active regions

more sunspots = higher solar output

Question 3

what sunspot cycle are we in now

Answer 3

cycle 25

Question 4

what happened to sunspots in 2008 and 2019

Answer 4

blank sun
no sunspots visible

like 1954 sun

means lower solar radiation output

Question 5

2020 sunspots

Answer 5

higher actvity from sun which suggest more spots

2014 they though sun had gone to sleeep

Question 6

do sunspots impact climate change

Answer 6

unclear

during medieval optimum there was warm summers and winters as lots of sunspots

Little Ice age in Maunder minimum = colder winter as less sunspots

Question 7

what does it mean by orbital forcing

Answer 7

milankovitch cycles

collective effects of changes in earths movements on climate over thousands of years

Question 8

what are the 3 recognised variations in changes of earths orbit around the sun?

Answer 8

eccentricity roll
obliquity axial tilt
precession wobble

Question 9

how long does eccentricity take for one cycle

Answer 9

100,000 yrs

Question 10

how long does obliquity take for one cycle

Answer 10

41,000 yrs

Question 11

how long does precession take for one cycle

Answer 11

26,000 yrs

Question 12

describe eccentricity

Answer 12

creates a rounded perfect circle and changes to elliptical circle due to grav forces

not a large impact on amount of insolation recieved in a yr but influneces lengths of seasons

high eccentricity = greater seasonal variation also linked to ice sheet dvelopment

Question 13

describe obliquity

Answer 13

tilt of earths axis of rotation

varies from 21.5 - 24.5 degrees

influnces solar radiation reaching earth

large tilt - dimishes contrast in insoltaion between low and high latitudes

(low tilt favours ice sheet developemnt due to low SR)

greater seasonal contrast - area towards sun in summer . tilted away in winter - affects high lats most

Question 14

describe precession

Answer 14

the season during which earths nearest the sun (perihelion) and furthest away (aphrlion) varies.

n. hemis tilted away from sun at aphelion - \

n hemis tilted towards sun at aphelion - / -favours ice sheet development lower sun radiation

Question 15

EVIDENCE of milankovitch cycles

Answer 15

cyclic deposits in s.spain - hard/soft layer etc

oxygen isotopes - measure size of ice sheet and temp of water

Question 16

oxygen ratios

Answer 16

16O ligher
17O
18O heavier

Question 17

where are more 16O found

Answer 17

clouds

older water

lighter and colder more

during interglacial periods not enriched in 180 but 16o returns quickly to oceans to maintain balance

Question 18

where are more 18O found

Answer 18

evaporation removes 16o leaving heavier 18o behind

during glacial periods oceans enriched in 18o as 16o stored in ice sheets and doesn’t return quickly to ocean

Question 19

define el nino

Answer 19

irreuglar warming of sea surface temps off peru and ecuador to central pacific

high air pressure in west/ low pressure in east

weakeneds trade winds

Question 20

define la nina

Answer 20

colder counterpart of el nino in eastern pacific

intense winds

strengthening of norm

Question 21

ENSO meaning

Answer 21

el nino southern oscillation

atmospheric pressure changes from east to west which influnces temp and rain on globe