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What is Weather?
I take
you to
the next
slide!
What is the Water Cycle?
What is Atmosphere?
How do weather balloons work?
I take
you back
a slide!
What is the Water Cycle?
Condensation and Clouds
Water vapor in the air gets cold and changes back into
liquid, forming clouds. This is called condensation.
You can see the same sort of thing at home... pour a
glass of cold water on a hot day and watch what
happens. Water forms on the outside of the glass. That
water didn't somehow leak through the glass! It actually
came from the air. Water vapor in the warm air, turns
back into liquid when it touches the cold glass.
Evaporation
Evaporation is when the sun heats up water
in rivers or lakes or the ocean and turns it into
vapor or steam. The water vapor or steam
leaves the river, lake or ocean and goes into
the air.
Precipitation
Precipitation occurs when so much
water has condensed that the air
cannot hold it anymore. The clouds get
heavy and water falls back to the earth
in the form of rain, hail, sleet or snow.
What is Atmosphere?
• The Earth's atmosphere consists, from the
ground up, of the troposphere, stratosphere,
mesosphere, thermosphere, and also the
magnetosphere. For now, we will only be
concerned with the troposphere which is
where weather occurs.
What is Atmosphere cont…?
• The atmosphere of Earth is made up of three
primary gases, oxygen, nitrogen, and argon. In
addition to these three gases, there are many
other gases in the atmosphere, in trace
amounts. Additionally there are small
particles, or particulates floating in the
atmosphere, such as dust, water, and pollen.
(allergens!)
Atmosphere Experiment!
So what if…
• Like any recipe the balance between amounts
of gas in the atmosphere is very delicate.
Take for example, Oxygen. Our atmosphere is
comprised of precisely 21% oxygen. Any
more and our atmosphere would be
incredibly unstable and flammable. Any less
and all animals would die off because they
couldn’t breathe!
Weather
• The weather is all around us, all the time. It
is an important part of our lives and one
that we cannot control. Instead the
weather often controls how and where we
live, what we do, what we wear and what
we eat. Someone who studies the weather
is called a meteorologist. Weather
predictions are made by forecasters who
you see on television.
Meterologist Jargon
• BAROMETRIC PRESSURE The pressure exerted by
the atmosphere at a given point. Its
measurement can be expressed in several ways.
• Hi An area of relative pressure maximum that
has diverging winds and a rotation opposite to
the earth's rotation
• Lo An area of a relative pressure minimum that
has converging winds and rotates in the same
direction as the earth.
How do weather balloons work?
• Twice a day, every day of the year,
weather balloons are released
simultaneously from almost 900
locations worldwide!
• Weather balloons, which are made of
latex or synthetic rubber (neoprene),
are filled with either hydrogen or
helium.
How do weather balloons work?
• An instrument called a radiosonde is
attached to the balloon to measure pressure,
temperature and relative humidity as it
ascends up into the atmosphere.
• By tracking the position of the radiosonde,
we can also calculate wind speed and wind
direction.