1
00:00:00,123 --> 00:00:01,741
in the previous video

2
00:00:01,741 --> 00:00:05,317
we have already talked about the idea that there are times of earth orbit

3
00:00:05,317 --> 00:00:06,896
when it is closer to the sun

4
00:00:06,896 --> 00:00:08,986
and when it is further from the sun

5
00:00:08,986 --> 00:00:11,726
when it is closer to the sun

6
00:00:11,726 --> 00:00:14,234
let's say this is the times of the earth when it is closer to the sun

7
00:00:14,234 --> 00:00:19,064
this is the perihelion.. perihelion.. perihelion..

8
00:00:19,064 --> 00:00:21,711
and when it furtherest from the sun

9
00:00:21,711 --> 00:00:23,568
and I'm exaggerating the difference

10
00:00:23,568 --> 00:00:28,305
this is aphelion.. this is the aphelion in our orbit.

11
00:00:28,305 --> 00:00:32,392
when we are furthest from the sun.. maybe our orbit looks something like this

12
00:00:32,392 --> 00:00:36,711
so maybe our orbit looks something...

13
00:00:36,711 --> 00:00:43,305
so maybe our orbit looks something like this over here

14
00:00:43,305 --> 00:00:46,800
and what i point our in the first video we discussed is that

15
00:00:46,800 --> 00:00:50,411
this is not the cause of the season

16
00:00:50,411 --> 00:00:53,568
even-though we are 3% closer.. right now

17
00:00:53,568 --> 00:00:56,030
when are orbited... will see in the future video..

18
00:00:56,030 --> 00:01:00,395
that the difference or the eccentricity or how ellecptical

19
00:01:00,395 --> 00:01:01,974
the orbit is

20
00:01:01,974 --> 00:01:03,042
does change over time

21
00:01:03,042 --> 00:01:05,736
how much it deviates from being circular

22
00:01:05,736 --> 00:01:08,569
that's how.. that one way to think about eccentricity

23
00:01:08,569 --> 00:01:10,380
that does change over time

24
00:01:10,380 --> 00:01:11,726
right now

25
00:01:11,726 --> 00:01:13,398
when we we are closest to the sun

26
00:01:13,398 --> 00:01:15,627
we are 3% closer than we are furthest from the sun

27
00:01:15,627 --> 00:01:19,844
3% closer than at aphelion

28
00:01:19,844 --> 00:01:22,408
and we point out in the first video that we discussed

29
00:01:22,408 --> 00:01:25,055
that this is not the cause of the seasons

30
00:01:25,055 --> 00:01:27,237
and in particular

31
00:01:27,237 --> 00:01:29,374
perliion where we are closest to the sun

32
00:01:29,374 --> 00:01:32,067
where we actually have the most radiation from the sun

33
00:01:32,067 --> 00:01:35,643
that's actually when we have the northern hemisphere

34
00:01:35,643 --> 00:01:37,733
when we have the northern hemisphere winter

35
00:01:37,733 --> 00:01:42,052
so this occurs right over here.. this occurs in January

36
00:01:42,052 --> 00:01:47,766
this occurs in January.. aphelion occurs in July.. occurs in July

37
00:01:47,766 --> 00:01:51,572
now based on this, this might lead to an interesting question

38
00:01:51,572 --> 00:01:57,903
because.. so let's think about January.. let's think about January

39
00:01:57,933 --> 00:01:59,374
when we are perhelion

40
00:01:59,374 --> 00:02:03,228
and let's think about July.. let's think about July.. we are in aphelion

41
00:02:03,228 --> 00:02:07,105
let me draw a quick globe right over here

42
00:02:07,120 --> 00:02:08,836
and let's make that the equator

43
00:02:08,836 --> 00:02:12,730
and I'll write that in both the situations.. in both the situations

44
00:02:12,730 --> 00:02:16,908
so in January is obviously when we have the northern hemisphere's winters are cold

45
00:02:16,970 --> 00:02:19,482
painted in blue right over here..

46
00:02:19,482 --> 00:02:23,067
it is winter

47
00:02:23,067 --> 00:02:26,406
and July it's when we have northern hemisphere's summer

48
00:02:26,406 --> 00:02:33,321
or the southern hemisphere's winter.. so then we have winter.. winter during July.

49
00:02:33,321 --> 00:02:35,068
in the southern hemisphere

50
00:02:35,068 --> 00:02:42,333
let's me put summer in a more summery color. i guess that orange is a pretty good color.. that's not orange..

51
00:02:42,333 --> 00:02:44,383
hers' orange.. alright..

52
00:02:44,383 --> 00:02:50,040
that's orange and that's orange.. so these are summer..

53
00:02:50,040 --> 00:02:52,118
summer

54
00:02:52,118 --> 00:02:54,954
so that's the summer in southern hemisphere

55
00:02:54,954 --> 00:02:57,241
which occurs during the winter in northern hemisphere

56
00:02:57,241 --> 00:02:58,589
and vice versa

57
00:02:58,589 --> 00:03:02,188
summer in the northern hemisphere occurs during winter in the southern hemisphere

58
00:03:02,188 --> 00:03:05,154
and so the question might be rising in your head

59
00:03:05,169 --> 00:03:08,744
and i did see a few comments in that first video asking this question

60
00:03:08,744 --> 00:03:10,059
and it's a good one

61
00:03:10,059 --> 00:03:14,607
and if we are closer.. if we are closer to the sun in January

62
00:03:14,607 --> 00:03:16,662
or we are really closest to the sun in January

63
00:03:16,677 --> 00:03:19,122
this is the perihelion right over here

64
00:03:19,122 --> 00:03:22,582
and so we are getting more solar radiation in January

65
00:03:22,582 --> 00:03:26,402
does that moderate the winter

66
00:03:26,402 --> 00:03:29,197
so does that moderate the winter..

67
00:03:29,197 --> 00:03:31,360
in the northern hemisphere

68
00:03:31,360 --> 00:03:32,957
or i guess another way to think about it..

69
00:03:32,988 --> 00:03:37,231
does it make summer in the southern hemisphere when we are closer to the sun

70
00:03:37,262 --> 00:03:39,730
does it make it more extreme

71
00:03:39,730 --> 00:03:44,138
does it make it more extreme or hotter and vice versa

72
00:03:44,138 --> 00:03:45,875
in July, when we are

73
00:03:45,931 --> 00:03:47,740
when we are furthest from the sun

74
00:03:47,786 --> 00:03:50,040
does that moderate the northern hemisphere winter

75
00:03:50,040 --> 00:03:51,656
because it is hot out there

76
00:03:51,656 --> 00:03:53,044
but hey it's little bit further from the sun

77
00:03:53,044 --> 00:03:56,795
and does that make the southern hemisphere winter colder

78
00:03:56,795 --> 00:03:58,762
so once again does it make this more extreme

79
00:03:58,762 --> 00:04:01,650
because it's already winter and we are further from the sun

80
00:04:01,650 --> 00:04:05,467
so maybe we are also getting less radiation

81
00:04:05,467 --> 00:04:07,067
and there's a couple of way to think about this

82
00:04:07,067 --> 00:04:11,313
1 -- it is true that when we are further, we are getting a little bit less radiation

83
00:04:11,328 --> 00:04:13,944
from the sun or we are getting heated up a little bit less

84
00:04:13,944 --> 00:04:19,679
but the one reality is that the southern hemisphere climate as a whole

85
00:04:19,679 --> 00:04:23,570
is not more extreme despite getting heated up

86
00:04:23,570 --> 00:04:26,800
getting more solar energy in the summer

87
00:04:26,800 --> 00:04:29,235
and getting less solar energy in the winter

88
00:04:29,235 --> 00:04:31,232
and the reason why this is not an extreme

89
00:04:31,232 --> 00:04:34,533
we draw the equator here.. just that we can separate our hemispheres

90
00:04:34,533 --> 00:04:35,975
the main reason it is believed

91
00:04:35,995 --> 00:04:42,298
that it is not more extreme.. it is that the southern hemisphere has a lot more water in it

92
00:04:42,298 --> 00:04:45,438
so just if you look at the surface of the southern hemisphere you are looking at a lot more water

93
00:04:45,438 --> 00:04:47,337
than the surface of the northern hemisphere

94
00:04:47,337 --> 00:04:49,425
this is of course the locator projection

95
00:04:49,425 --> 00:04:52,037
this distorts things so that the things near the pole

96
00:04:52,037 --> 00:04:56,133
gets really kind of built up to look really huge even though they really aren't that big..

97
00:04:56,133 --> 00:05:00,304
Greenland really isn't larger than south america

98
00:05:00,304 --> 00:05:01,400
it just spreads the mouth so that you can kind of

99
00:05:01,400 --> 00:05:05,041
so that you can... flat the map to speak...

100
00:05:05,041 --> 00:05:06,898
so the southern hemisphere has more water

101
00:05:06,898 --> 00:05:08,709
as you may have learned in chemistry class

102
00:05:08,709 --> 00:05:10,706
water has the highest specific heat

103
00:05:10,706 --> 00:05:18,612
highest specific energy.. it takes more energy, more heat to raise water a degree

104
00:05:18,612 --> 00:05:22,482
than it does takes to raise land a degree

105
00:05:22,482 --> 00:05:25,228
and so water can absorb more energy

106
00:05:25,443 --> 00:05:29,220
or when there is less energy, water will release more energy

107
00:05:29,220 --> 00:05:31,733
without droping as much of a temperature

108
00:05:31,733 --> 00:05:34,065
so water has a moderating influence

109
00:05:34,065 --> 00:05:36,991
water has a moderating influence on the climate

110
00:05:36,991 --> 00:05:40,381
so eventhough summers in the southern hemisphere

111
00:05:40,381 --> 00:05:43,632
actually are getting more radiations than the summers in the northern hemisphere

112
00:05:43,632 --> 00:05:47,905
that's moderating on the actual temperature.. because the water is believed to absorb

113
00:05:47,905 --> 00:05:51,898
more of that heat without changing the temperature as dramatically

114
00:05:51,898 --> 00:05:54,731
now with that said, it is true

115
00:05:54,731 --> 00:06:02,068
that in general Antarctica is colder.. Antarctica is colder.. it is than the north pole

116
00:06:02,222 --> 00:06:05,041
but the main reason why antartica is colder besides the fact

117
00:06:05,041 --> 00:06:06,713
that it is in land.. as suppose to antartica being...

118
00:06:06,713 --> 00:06:11,403
...as suppose to the north pole being the centre of the artic ocean

119
00:06:11,403 --> 00:06:15,722
is that it is actually a huge.. very high altitude of ice sheet

120
00:06:15,722 --> 00:06:19,541
and so for the altitude for most of the Antarctica is around 8000 feet

121
00:06:19,572 --> 00:06:22,317
so it's like an alphine altitude

122
00:06:22,317 --> 00:06:24,385
so the main reason why it's colder is

123
00:06:24,385 --> 00:06:27,239
you know it's possibly being further away from the sun

124
00:06:27,239 --> 00:06:28,400
and winter might play some role there

125
00:06:28,400 --> 00:06:31,558
but the main reason why it's colder is that it's at a much higher altitude

126
00:06:31,558 --> 00:06:34,133
and it's some degree insulated from the water

127
00:06:34,133 --> 00:06:35,970
or I guess you could say it's on the land

128
00:06:35,970 --> 00:06:40,200
so especially during the long winter it's going to get that much colder

129
00:06:40,200 --> 00:06:41,403
but i'll leave you there and

130
00:06:41,403 --> 00:06:44,354
and to some degree this is the other aspect of it

131
00:06:44,354 --> 00:06:48,733
during the summers... you know.. all of this stuff is super complicated

132
00:06:48,733 --> 00:06:51,388
so you can.. you can just drop one rule of thumb and say this it the reason..

133
00:06:51,388 --> 00:06:52,410
these are all are influencers

134
00:06:52,410 --> 00:06:56,071
is that if you have a large super-large ice shield sheet

135
00:06:56,071 --> 00:07:00,182
it's also more likely to reflect more of the energy

136
00:07:00,197 --> 00:07:04,090
because it's white as suppose to a darker color like the ocean or the land

137
00:07:04,090 --> 00:07:07,922
so you can think about all of those factors but the general answer is -- it's a good question

138
00:07:07,922 --> 00:07:10,057
but overall the climate in the southern hemisphere (actually it has to be northern hemisphere) is

139
00:07:10,057 --> 00:07:13,958
not more extreme than the climate in the southern hemisphere

140
00:07:13,958 --> 99:59:59,999
even though antartica is colder