Transcript What is a cloud?

Warm up
What’s the difference between
Global Warming
Greenhouse Effect
Ozone Hole
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Ozone
O3
CFCs break O3
molecules
Absorbs UV rays in the
stratosphere
 Depletion allows UV
rays to reach surface
 Sunburn, skin cancer,
plankton die offs
 Green House/Global
Warming
 Too much heat trapped
in atmosphere
 CO2 & other gases
absorbs infrared (heat)
 Melting ice, increased
temperatures, weather
patterns changing
What is a cloud?
Phase Changes
 Melting, evaporate – add energy (heat)
 Freeze, condense – lose energy (heat) cooling
 Condensation – loses energy, gas to a liquid
(dew forms, cans or glasses “sweat”)
 Frost – lose energy (cooling), ice particles
form on surfaces
humidity
 Amount of water vapor in the air
 Saturation – when air filled with the amount
of water vapor it can hold (depends on
temperature)
 Relative humidity –
 Dew point- temp. at which saturation occurs,
dew/ condensation forms
homework
 Create a cartoon strip showing how clouds
form.
Why study clouds
We can’t see air or moving air
1. Clouds give us lots of
information about how the air is
moving
2. Clouds foretell approaching
weather
3. Give us clues to other
characteristics.
Why can we see clouds?
 Density of water 1g/cm3
 Density of cloud 0.5g/m3
 Density of rainy air 0.83g/m3
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Warm air holds more H2O than cold air
Evaporation takes energy
Condensation releases energy
Air cools as it rises
Warms as it sinks
 Rises high enough for water to condense –
condensation level
Condensation level
 How do we determine the condensation
level? (Height that clouds start forming?) –
when the dew point and the temperature are
the same
 Dew point lowers 2°C per km
 Temp decreases 10°C per km
Means of Formation
 Convection – warm air rises, cools to dew
point, clouds form
 Mountain effect – air rises because
mountains are in the way, cools to dew
point, clouds form
 Frontal effect – when air masses with
different characteristic meet, ex: warm moist
touches cold dry
Precipitation
 Clouds get heavy
 Water droplets – grow from collisions
 snow flakes grow from collisions and the
addition of super-cooled water vapor
 Fall
Types of Precipitation
 Snow – stays frozen., below 0C
 Freezing rain – frozen, melts, freezes on contact,
surface is near 0C
 Sleet – frozen, melts, refreezes into ice pellets,
surface is below 0C
 Rain – may start as snow or water, falls through
warmer air, above 0C
 Hail – associated with cumulonimbus clouds,
falling ice falls, gets caught updraft grows
Warm up
 What’s the most confusing thing in Chapter
18?
 What the most interesting thing in Chapter
18?
Where is Precip Likely
 Clouds
 The side of mountains where the wind is
coming from
 Convection evaporating water, clouds form
etc
 Fronts – boundary between different air
masses
 Places with lots of evaporation
Test format
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Multiple choice
Open response
Relative humidity chart – use it
Cloud altitude chart – cloud type and
weather associated with those clouds
 Identify cloud pictures
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What are the benefits to living in an igloo?
Why did I still see ice on my way to school?
Why do you feel cold when you are wet?
Why was there sleet yesterday?
Why can you have fat clouds next to a clear
patch of sky?
A,B
C,D