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If you shine a torch directly at the ground it will be much brighter than if you shine it at an angle.
The same goes for the sun shining on the earth.

The earth orbits the sun at an angle 23.5 degrees,
Now the brightness of light depends on the square of the distance.
so in winter, only (cos23.5)² x 100% ≈ 84% of the suns rays hit the earth directly
that is, the sunlight is 16% less bright in winter than in spring due to the angle of orbit

on the other hand
the earth is on average 92587000 miles from the sun
so if the sun is 1000000 miles closer
it is only (1000000/92587000) x 100% ≈ 1.1% closer
and the brightness of light depends on the square of the distance so if the sun is 1.1% closer
it is (1.1)² ≈ 1.2% brighter

so, in total, taking into account the angle and the distance,
the sun is 16% - 1.2% ≈ 15% less bright in winter than spring Which means it is colder.

Although this is an approximation, the important thing to realize is that the angle of orbit has a much greater effect on the temperature than the 1000000 miles

,.,,.,

2007-11-10 00:30:58 · answer #1 · answered by The Wolf 6 · 4 0

A biased question!

In Australia, it is much hotter in summer, when we are closer to the Sun (in January) and colder in winter (July) when we are further away.

In 2008:
perihelion, Jan. 2: 147,096,448 km
aphelion, July 4: 152,104,136 km
(centre to centre)

The flux (rate at which heat arrives) is not that different, because the difference in distance is relatively small.

Average flux received at Earth (before being reflected by clouds or absorbed by atmosphere, or reflected by snow...) is 1370 W/m^2 (Watts per square metre)

In January, it is 3% more (47 W/m^2 more) and in July it is 3% less. (The flux varies as the inverse square of the distance).

However, the rate at which heat reaches the ground depends also on the angle the Sun makes with the vertical.

If the Sun were directly overhead, a one square metre patch of field would receive the full 1370 W (minus what is reflected and absorbed by the atmosphere).

If you live around 45 degrees North latitude, the Sun does not get overhead.

In summer, it may reach 45 + 23 = 68 degrees at noon. The heat rate is 1323*Sin(68) = 1226 at noon (minus reflection and absorption). And the days are much longer.

In winter, it can only reach 45-23 = 22 at noon. The heat rate is 1417*Sin(22) = 531 W at noon (minus stuff...) AND the days are much shorter, giving even less time for the integration of heat over the day.

2007-11-10 08:41:34 · answer #2 · answered by Raymond 7 · 4 0

An ant underneath Black Wolfs torch would see 2 things:

1) When the torch is shining straight down the ant would see the torch directly above him.

2) When the torch is shining from an angle, the ant would see the torch lower down in the "sky". It would be nearer the horizon.

For us, it's the same. During the morning the sun is near the horizon, at midday it is higher up in the sky. During the winter, however, the sun is quite near to the horizon, no matter if it is morning or midday. And in some parts of the world it is so low in the sky that it can't even get over the horizon at all - it is nighttime for months.

2007-11-10 09:01:24 · answer #3 · answered by some_pixels_on_a_screen 3 · 1 0

angle of the sun to the earth
that's why the other hemisphere has summer

now you can learn what that figure 8 means
in the Pacific Ocean on a globe - it's the tangent of the Sun!

all the best

2007-11-10 08:27:11 · answer #4 · answered by tom4bucs 7 · 0 0

Due to the diggerent angle that the suns rays have to travel to reach Earth.

2007-11-10 08:28:57 · answer #5 · answered by woodburner 4 · 1 0

Its summer in the southern hemisphere when we have our winter. Its due to the angle of the earth.

2007-11-10 08:35:50 · answer #6 · answered by Anonymous · 0 0

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