Transcript Factors that affect weather

Factors that affect weather
Air pressure, humidity, temperature,
precipitation
The Water Cycle
1.
2.
3.
4.
Take out a clean sheet of paper.
Number your paper 1-7 leaving half of the page
for a picture.
Write the 7 definitions on the following slide.
Wait for Mrs. Couch to draw the picture (Yes you
have to draw the picture)
The Parts of the Water Cycle
1.
2.
3.
4.
5.
Evaporation
Condensation
Precipitation
Deposition
Sublimation
6. Infiltration
7. Percolation
8. Surface Run off
9. Transpiration
10.Urination
11.Accumulation
Important parts of the water cycle
1. Evaporation – liquid to gas
2. Condensation – gas to liquid
3. Precipitation – any form of water
falling from the clouds to the ground
4. Transpiration – plant sweat
5. Surface Run off – water moving over
land from higher to lower ground
6. Infiltration – Water fills the space
between particles of soil
The water cycle – cont.
1. Percolation – Ground water moving
below earth’s surface
2. Accumulation – a big pile of water, pond,
puddle, ocean, river etc.
3. Urination – liquid waste – yuk
4. Sublimation – Water vapor freezes into a
solid – makes snow
5. Deposition – Solid that vaporizes – skips
the liquid phase
Humidity
Humidity and Relative Humidity
• Humidity – the
amount of water
vapor in the
atmosphere
• Relative Humidity =
The actual amount of
water vapor in the air
divided by the
maximum amount of
water vapor the air
can hold
Measured with
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•
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A sling psychrometer
Made of 2 thermometers
A wet bulb
A dry bulb
How it works
1 – sling it over your head for
20 seconds so air blows
over the thermometers
2 – the wet bulb is cooled by
evaporation
3 – therefore the
temperature of the wet
bulb is < the dry bulb
4 – use the chart to
compare the
temperatures
Dew Point
• Dew Point = The
temperature at which air
would have to cool to
reach saturation (all of
the water vapor it could
hold)
• The dew point will never
be greater than the
temperature!!
• BUT if it is equal –
humidity = 100% - causes
condensation  fog,
clouds, precipitation
Check out the Dew point
Calculator!
How do clouds form?
Remember:
**Warm air holds more water than cold air
**As air rises it cools
Condensation:
•
occurs when there is enough water vapor in the air
•
tiny particles must be present for the water to stick to
Dew Point:
•
The temperature at which condensation occurs
Clouds form when warm air rises and the water vapor the
air holds is cooled to the dew point
Let’s put this in your own words!!!
Important Cloud
Vocabulary
• Cirro – curly • Alto –
or whispy
middle
• Nimbus –
• Cumulo rain
heaped
• Stratus layer
3 Ways to Identify Clouds
1. Altitude
2. Shape
3. The weather they bring
Let’s look at some examples:
Cumulo (heap/pile)
• Fair weather
• 2 – 18 km
Cirrus (curly/whispy)
• Above 6 km – very high in the sky
• Made of ice crystals
Stratus (layer – spread out)
• Cover all or most of the sky
• Thicker – brings rain/snow/drizzle
Other Clouds
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•
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Nimbo – Rain
Alto – middle 2 – 6 km
Fog – stratus clouds low to the ground
Cumulonimbus – Thunderheads
Contrails – Jet trails
Factors that affect weather
Air pressure, humidity, temperature,
precipitation
Remember …
• Air has mass and takes up space.
• Air pressure – the mass of the air being
pulled down on an area of the earth’s
surface.
• It pushes in all directions - it does not
crush objects
2 things that affect air pressure
• Temperature
• The amount of air
above it
Air moves?
• Yes – air moves from areas of high
pressure to low pressure quickly
Weather Indicators
• Falling Air Pressure
• Storms
• Rising Air Pressure
• Good Weather
Measuring Air Pressure –
Barometer
• Mercury - glass tube
open at the bottom In
a glass dish of
mercury
• Measured in inches
• Aneroid Barometer –
air tight metal
chamber
• The wall flex in and
out with the changes
in air pressure.
• Measured in millibars
• 1 inch = 33.87 mb
Cheat sheet
• Elevation
• Elevation
• Pressure
• Pressure
• Pressure
• Pressure
• Density
• Density
• Elevation
• Elevation
• Density
• Density
Precipitation
What is precipitation?
• Any form of water that falls
from the clouds to the
ground
Rain
• The most common
• Must be at least
.5mm in diameter
• Any smaller =mist
or drizzle
• Which falls from
nimbostratus
clouds
Sleet
• Occurs when
rain falls through
a layer of air
below freezing
• Freezes into
solid ice before it
hits the ground
• Smaller than 5
mm
Freezing Rain
• Falls as rain and
freezes when it
touches a surface
below freezing
• Does not freeze in
the air
Hail
• Ice > than 5 mm in
diameter
• ONLY from
cumulonimbus clouds
• Adds layers from up
and down drafts in the
cloud
• Can damage property
Snow
• Water vapor that
turns directly into
ice (not frozen
liquid water)
• Each snowflake
has six sides and
is different
How is it measured?
• Liquid Precipitation –
rain is measured with
a rain gauge
• Snow is measured
with a ruler
Drought
Long periods of
unusually low
precipitation
Other Terms:
1) Drought: long period of low
precipitation
2) Cloud Seeding: dropping tiny
crystals of dry ice (solid CO2)
and silver iodide sprinkled into
clouds from planes. May be
used to clear fog at airports.