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[music playing]

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- Everyone knows that Earth
gets light energy

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and heat energy from the Sun,

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but what happens
to this energy?

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Some of the energy gets
absorbed by the atmosphere,

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oceans, the land,

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but some of it gets reflected
back to space.

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Sounds complicated, doesn't it?

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Let's talk to Patrick Taylor
from NASA

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to find out what Earth's
energy balance is all about.

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- Earth's energy balance
is really that.

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It's just a balance

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between the amount of energy
that's coming in

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and the amount of energy
that's leaving the Earth.

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So balancing
Earth's energy budget

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is a lot like balancing
an equation.

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We'll say X is incoming energy,

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and that has to equal Y,
which is outgoing energy.

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So when these two are equal,

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then we say Earth's energy
is in balance.

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So energy from the Sun comes
to us in the form of light,

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and that is--
it's also known as radiation.

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It can be absorbed
in the atmosphere.

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It can also then
be reflected back to space,

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either by the clouds
or by the polar ice caps,

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a very bright surface.

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The third thing
that can happen too is,

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it can be absorbed
by the surface.

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A total of 70% of the energy

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is actually absorbed
in the Earth's system,

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and only 30% is reflected
back to space.

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Small changes
in Earth's energy balance

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can have very big impacts
on Earth's climate,

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changing the frequency
of heat waves

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and cold waves,

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the frequency of hurricanes,

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as well as our ability to farm,

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the availability
of fresh water and clean air,

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impacting human health.

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So we've been studying
Earth's energy balance

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for more than 40 years,

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including the Nimbus 7
satellite,

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the Earth Radiation Budget
Experiment in the mid-1980s,

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and also since the late 1990s

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with the launch of CERES,

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which is Clouds and the Earth's
Radiant Energy Instrument,

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and that's actually the science
team that I'm a part of.

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So to understand what controls
Earth's energy balance,

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we also observe a lot of other
different types of information.

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Having a steady supply of data
is really important,

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especially for studying
Earth's energy balance.

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The small changes
in Earth's energy balance

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make a really big impact
on Earth's climate,

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and having a long data record
is really important

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for assessing those changes.

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Earth's energy budget
is essentially

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adding up all of the terms,

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but when Earth's energy budget
equals zero--

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so if you have incoming energy
plus outgoing energy,

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and they equal zero,
or they balance each other,

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that's when you have
Earth's energy balance.

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- More energy coming in
than what you give off,

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and the system will heat up.

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More energy going out
than coming in,

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and the system will cool down.

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Planet Earth
with its atmosphere

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has just the right balance
for life to thrive,

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and that's what makes Earth
a great place to live,

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no matter what the weather.

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Hey, here comes the sun!

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See you next time
on "Real World."