Transcript Water in the Air Section 1

Water in the Air
Section 1
Understanding Weather
Chapter 15
The Water cycle
• The continuous changing of water from a
liquid to a solid or gas, and back to a
liquid.
• The main parts of the cycle are…
-Evaporation
-Condensation
-Precipitation
Humidity
• Humidity is the amount of water or
moisture in the air.
• Not all Air can contain the same amount of
water…
• The warmer air is, the more water vapor it
can hold.
• The cooler air is the less water it can hold.
Relative Humidity
• This is the amount of water the air is
caring as a Percent of what it can
actually carry.
• Remember, all air can carry 100%, this is
called saturated air (it could not possibly
hold any more)
If our room is 80º and Mr. Perez’s room is
85º and the air is saturated in both, what
room will have more water?
The process of condensation
• Condensation is the process in which water
vapor changes back into a liquid, this may
happen in two ways.
• 1) the air is saturated and can hold no more
water vapor, so it transforms into a liquid again.
• 2) the air contains water vapor (only 80%), the
temperature decreases, and now that it can’t
hold as much water, it is at 100% humidity.
Clouds
• Clouds are a collection of millions of tiny
water droplets, or ice crystals.
• Clouds form when warm air rises and
cools, causing condensation.
• In order for water vapor to form a water
drop, it needs something to attach itself to.
• This is called condensation nuclei, and it
can be dust, smoke or salt that is floating
in the air.
Types of clouds
• Three main types of clouds…
• Cumulus: Big puffy white clouds
• Stratus clouds: large blanket-like clouds.
• Cirrus clouds: thin feathery clouds
• If the cloud name also contains the words nimbo
or nimbus, this means that it will rain.
Cumulus clouds
• Large puffy cotton candy looking.
• These clouds form when warm air rises.
• These clouds signify good weather, but
when they get too big and change color
(gray) they mean rain!
Stratus clouds
• These clouds look like large blankets in
the sky.
• They block out the sun.
• Are caused by gentle lifting of large bodies
of air into the atmosphere.
Cirrus clouds
• Very thin clouds
• Form in very high
altitudes
• Caused by strong
winds
Precipitation
• Water that fall to the ground is called
precipitation.
• There are four main type of precipitation.
-rain, snow, sleet, and hail.
rain
• This is the most
common type of
precipitation.
• A water droplet usually
starts at about the size
of a period at the end of
a sentence, and may
get up to 100 times
bigger before it falls
Snow
• Snow is precipitation
that freezes directly
from a gas and fall to
the ground.
sleet
• Rain that falls through a layer of freezing
air and becomes a solid
hail
• Rain that falls through a layer of freezing
air and becomes a solid, then is pushed
back up into the clouds by strong winds.
• It falls again and gets wet, and freezes
even bigger.
• This may happen many times, that’s why
hail may be as small as a pea or as big as
a golf ball.