Download Weather Study Guide

Weather Study Guide
Heat transfer: When heat is
transferred from one piece of matter to
another
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Conduction: transfer of heat between
substances that are in direct contact
with each other, the better the
conductor, the more rapidly heat will
transfer
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Convection: the up and down
movement of gases and liquids caused by
heat transfer – due to density
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Radiation: electromagnetic waves
travel through space, it is called
radiation. When the waves come in
contact with an object, the waves
transfer the heat to that object
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Light: form of electromagnetic energy
made up tiny bundles of energy
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Light travels in waves
Electromagnetic Spectrum
 Different wavelengths = different
kinds of waves
 Longer wavelengths are less harmful
 Visible light: light we can see
 Form of radiation
Reflection: bouncing of a wave after
striking a barrier
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Refraction: bending of a wave as it moves
from one medium to another
 Water gains energy when it is getting
hotter
 Water loses energy when it is getting
colder
 Energy is gained or lost when water
changes phases
 Transpiration: evaporation of water
from the stems or leaves of plants
Reminder:
Water vapor  Liquid: Condensation
Liquid  Water Vapor: Evaporation
Liquid  Ice: Freezing
Ice  Liquid: Melting
Specific heat: amount of energy needed
to raise 1 gram of a substance one degree
(highest specific heat is liquid water so
water doesn’t heat up easily or cool down
easily)
Humidity and Dew Point
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Humidity: water vapor in the
atmosphere
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Controlled by how much water
The Atmosphere
 Troposphere: lowest layer; what we
breathe; weather happens here
 Stratosphere: second layer; airplanes
travel here; contains the ozone layer
 Mesosphere: third layer
 Thermosphere: fourth layer
 Exosphere: last layer, mostly empty
space
In between the layers…
 Tropopause: Division between
troposphere and stratosphere
 Stratopause: Division between
stratosphere and mesosphere
 Mesopause: Division between mesophere
and thermosphere
Air Masses and Fronts
 Air mass: large body of air, in it
temperature and moisture levels are
similar
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is evaporating
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The hotter the temperature, the
more water evaporates, so the
humidity is higher
When the rate of condensation and
evaporation is equal, the air is saturated
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When the air is “full” – meaning
no more water can evaporate into
the air
Dew: if the air is saturated, water
vapor comes out of the air as dew (it’s
the water you find on leaves/grass in the
morning – without it raining)
Dew point: the temperature where
condensation and evaporation are equal
(the air is completely saturated)
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At temperatures below the dew
point, condensation (liquid water
droplets) form
Relative humidity: the ratio of the
amount of water vapor in the air to the
amount of water vapor needed to reach
saturation at a given temperature (how
close the air is to dew point or
saturation)
Psychrometer: tool used to measure
humidity, has two thermometer bulbs
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One bulb is dry, one is wet
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Use the difference to calculate
the relative humidity
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Wet bulb temperature is always
lower
Atmospheric pressure: the pressure
exerted (put) on the surface by the
atmosphere (the gas in the atmosphere),
exerted equally in all directions (up,
down, and sideways)
 Atmospheric pressure decreases as
altitudes increases
Air pressure changes with differences
in temperature and the amount of water
vapor in air
As temperature increases, pressure at
sea level decreases
As the amount of water vapor
increases, pressure at sea level decreases
Pressure measured with barometers
Unit = mb (millibars)
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o Air masses take the properties of
the area of the Earth they are over
Air masses over land are continental (c)
o Dry, form over large landmasses
Air masses over oceans are maritime (m)
o Moist, formed over large bodies of
water
Air masses formed over warm areas
(closer to equator) are tropical (T)
Air masses formed over cold regions are
polar (P)
Four main kinds of air masses: cP, cT,
mP, mT
There is also an arctic air mass that
covers the poles
Cold front: cold air mass overtakes a
warm air mass, lifts warm mass, often
creates short but violent storms
Warm front: when a cold air mass
retreats (leaves) from an area, less dense
air rises over it, generally causes
precipitation and sometimes violent
weather
Stationary front: when the meeting air
masses move very slowly or not at all
Occluded front: forms when a cold air
mass overtakes a warm air mass and
lifts the warm air mass off the ground
and over another mass (involves three
masses)
Pressure differences in the
atmosphere cause the movement of air
worldwide – air moves from high
pressure regions to low pressure regions
High pressure regions: where cold air
sinks towards the surface, wind (or air)
moves outwards, clockwise and outward
Low pressure regions: where warm air
rises away from the surface, wind moves
inward and counterclockwise
Wind always moves from areas of
high to low pressure
The bigger the difference in pressure,
the stronger the wind
Thunderstorm: a usually brief, heavy
storm, that consists of rain, strong
winds, lightning, and thunder
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Hurricane: a severe storm that
develops over tropical oceans and whose
strong winds of more than 120 km/h
spiral in towards the intensely lowpressure storm center (the eye)
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Tornado: a destructive, rotating
column of air that has very high wind
speeds and that maybe visible as a
funnel shaped cloud
Ways to prepare for a hurricane
 Have food prepared
 Have a place to hide/evacuation route
 Have emergency supplies ready:
water, flashlights etc
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Clouds form when small water
droplets or ice crystals suspended in the
air gather around pieces of dust or salt
or ice; formed by condensation
Stratus cloud: flat uniform base,
form at low altitudes
Cumulus: look like cotton balls,
fluffy, low level
Cirrus: feathery cloud made of ice
crystals that has the highest altitude
Fog: condensation formed at low
altitudes (similar to really low clouds)
Station model: states weather
conditions in a specific location, can be
recorded on a weather map
Weather map: shows weather
conditions using symbols, colors, and
isobars (isobar = line of equal AIR
PRESSURE)
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When isobars are close together, the
wind is stronger (the map of air pressure
that looks like a contour map)
Wind direction is measured with a
wind vane
Wind speed is measured with an
anemometer
3 zones, or wind systems in each
hemisphere; direction describes where
the wind comes from
 Polar easterlies
 Prevailing westerlies
 Trade winds
Coriolis effect: the Earth rotating
causes the wind to curve
Jet stream: small band/stream of
fast wind
Adiabatic cooling: the process by
which the temperature of an air mass
decreases as the air mass rises and
expands
As air rises and goes over a mountain
it expands and cools down
Global Warming

CO2 and methane contribute to global
warming
 There has been an increase in CO2
due to human activity, started 100
years ago with the Industrial
Revolution
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What could happen if global warming
increases the temperature?
 The ice caps would melt and the
sea level would rise
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What can we do?
 Decrease our use of fossil fuels –
save electricity! Use renewable
sources of energy like solar energy
Ocean Currents
 Also follow convection! (warmer ocean water rises, cooler sinks)
 Follows the same patterns as global wind patterns