Download warm air

3/18/15
AIM: How does solar heating and
water vapor in the atmosphere affect
weather?
 DO NOW: How does weather affect your life?

HOMEWORK: Finish all Vocabulary
 P.454 Figure 1“Identifying”
 P. 455 figure 2 “infer”
 P 456 “Reading check”

3/19/15
AIM: How does solar heating and water
vapor in the atmosphere affect
weather?
 DO NOW: What factors affect the
weather?
 HOMEWORK p.461 # 1-5

3/23
AIM: How can clouds help us
determine the weather?
Do Now: Describe the type and shape
of clouds on a rainy day and on a sunny
day
 HOMEWORK: “Types of clouds”
handout

What am I?
You can’t see me, but you feel
me, you can’t touch me, but I
can touch you. I have been
called the “Breathe of the
Gods”, or the killer and giver of
life, gentle and fierce, friendly
and enemy, angry and happy.
What am I?
WIND
Weather is....
 The
current state of the
atmosphere...what is happening
right now
 The sun provides the energy that
drives the Earth’s weather
Main points to remember as
we learn about weather:
The sun warms the earth’s surface and
therefore all the air above the surface
 The earth is warmed most at the
equator and least at the poles---why?
 The air above land is warmed more
quickly than air above water.
 Warm air expands and rises, creating an
area of low pressure; cold air is dense
and sinks, creating an area of high
pressure

Weather Factors

•
FACTORS
TEMPERATURE=
the average motion of molecules
↑ TEMP= ↑movement of molecules= feels hot
↓ TEMP= ↓movement of molecules= feels cold
Air Pressure

Warm air= expanding or rising air=
leaves behind Low pressure

Cold Air =sinking air= leaves an area
of High pressure
Humidity and Relative
Humidity
The amount of water vapor present
in the air
Relative Humidity -is a measure of
the amount of water vapor present in
the air compared to the amount needed
for saturation at a specific temperature
Fig.4 page 457
Water in the Atmosphere:
Humidity (detailed)

Humidity: measure of the amount of water
vapor stuck between molecules in the air. The
air’s ability to hold water depends on the air
temp

The hotter the air, the more water the
air can hold
Cold air: molecules move slower so droplets of
water can start to stick together=condensation
 Relative humidity: the amount of water vapor(%)
compared to the amount the air can hold- tool used
is a psychrometer.
 100%=air is saturated

Relative humidity
If you hear a weather forecaster say
that the relative humidity is 50% it
means=
 The air contains 50% of the water
needed for the air to be saturated

DEW POINT
The temperature at which air is
saturated and condensation forms
 Changes with the amount of water
vapor in the air
 When air near the ground cools to its
dew point, water vapor condenses
and forms dew

APPLYING MATH p457
WIND
Why can you fly a kite on some days
but not others?
 Kites fly because air is moving from
regions of high pressure to low pressure
 Warm air is less dense and expands
causing low atmospheric pressure.
 Cool air is more dense and has higher
atmospheric pressure

Wind
Air moving in a specific
direction
 Warm, expanding air
has low atmospheric
pressure
 Cool air is dense, sinks
and has high
atmospheric pressure

 Wind results
because air moves from
areas of high to low
HOW TO MEASURE WIND
DIRECTION AND SPEED
Wind Direction
 Wind vane (has an arrow that points in the
direction from which the wind is blowing)
 Wind sock= has one open end that catches
the wind causing the sock to point in the
direction from which wind is blowing
 Wind speed= measured using an
anemometers ( rotating cuffs that spin
faster when the wind is strong)

REVIEW: What causes winds?
A wind is a
horizontal
movement of air
from a area of
high pressure to
an area of low
pressure
 It is this
difference in
pressure that
makes the air
move=wind

Winds are measured
by direction and
speed
 The anemometer
is the tool we use
to measure this
 Wind chill=↑
cooling the wind
causes

Review ch. 15

Local Winds
The land cools and heats faster than the ocean.
Water holds heat longer than land, and takes longer
to heat or cool.
During the day, the land
SEA BREEZE
gets hotter faster than the
water. The heated air
rises, leaving behind an
area of low pressure.
Wind from the cooler sea
blows in to take the place
of that warmer air. These
happen during the day!
Land Breezes
Review ch 15
At night the lands cools off faster than
the sea. Cool air sinks creating an area
of high pressure. Wind blows from the
land to the sea.
Cloud Formation
Form when warm air is forced upward,
expands and cools
 Clouds form when water vapor
condenses on particles (dust, salt, etc)
in the air (RELATIVE HUMIDITY IS
100%)
 The temperature in which condensation
begins is called the dew point

Clouds
Masses of small water droplets or tiny ice
crystals that float in the air.
 Why don’t clouds fall??


Clouds are classified by their shape and
height (vary with temp., pressure, and
water vapor in the atmosphere
SHAPE OF CLOUDS
3 main types are cirrus, cumulus, and stratus.
 LATIN ROOTS
- Cirus comes from the word meaning “lock of
hair”
- Cumulus come from the word meaning “heap”
- Stratus comes from the word meaning layer
- Nimbus come from the word meaning “rain
bearing”
 Other clouds are a mixture of these three main types.

TYPES OF CLOUDS
Cirrus Clouds: wispy, feathery clouds
 Cirro- means “curled” or “feathery”
-comes from a word meaning “lock of
hair”

**Form only at high
levels, therefore are made
of ice crystals
-Usually signal of a clear
day
Types of Clouds
Cumulus Clouds:
are puffy white cotton ball looking clouds
 Cumulo- means “heaped” or “piled”


***Usually signal good weather, but if
the atmosphere is unstable, can build
into towering clouds that produce
showers and thunderstorms.
Cumulonimbus Clouds
These are thunderstorm clouds
 NIMBUS= rain

Stratus Clouds
Stratus Clouds: clouds that form in flat
layers- cover all or most of the sky and are
low level clouds
 When air is cooled to its dew point near the
ground it forms a status cloud called FOG

Clouds classified by height=
Cirro- high clouds
 Alto=middle elevation clouds
 Strato= low elevation

Ex. Cirrostratus-> made of ice crystals
and form high in the Earths
atmosphere
 Ex. Altostratus-> form in middle layers

Rain or Snow??
- Clouds associated with rain or snow
usually have the word “nimbus”
(Latin for dark rain cloud) attached
to them
 CUMULONIMBUS-when a cumulus
cloud grows into a thunder storm
 Nimbostratus-layered clouds that can
bring long, steady rain or snow

Other Cloud Types
Cirrocumulus
Stratocumulus
Cirrostratus
Cumulonimbus
More Cloud Types
Altostratus
Altocumulus
Nimbostratus
Precipitation
 Water that falls from the clouds
 Air temperature determines the form of
precipitation that falls
 4 main types of Precipitation:
 Rain, Sleet, Snow and Hail=
-precipitation in the form of lumps of ice
-HAIL forms in cumulonimbus clouds of
thunderstorms when water freezes
Types of Precipitation
Rain
Sleet
Snow
Hail
WEATHER PATTERNS
SECTION 2
 AIM: How is weather associated with fronts
and low and high pressure?
 DO NOW: How can we use clouds as an
indicator of severe weather
 Homework: Page 463 Reading check
-Page 464 Figure 11 , DESCRIBE: What type of weather
occurs at front boundaries
-Page 465 Figure 12- IDENTIFY some things that tall
cumulonimbus clouds produce
Air Masses
 A large body of air that has
properties similar to the
part of the Earth’s surface
over which it develops.
Air Masses
Example: an air mass that develops
over land is dry compared to one
that develops over water
 If developed in the tropics it is
warmer than that which developed
over colder regions

Air Mass Map
HIGHS AND LOWS

Pressure Systems
-descending (going down)=H pressure
-ascending (going up)=L pressure
Weather Foldable
Warm front
 Cold front
 Occluded front
 Stationary Front

Fronts: the boundary between 2
air masses

Warm Front: warm air slides over
departing cold air- large bands of
precipitation form
This is
the
symbol
on a
map for
a warm
front
Cold Fronts

This is the symbol
for a cold front
Cold air pushes under a warm air mass.
Warm air rises quickly=narrow bands of
violent storms form
Occluded Front

This is the
weather map
symbol for an
occluded front
2 air masses merge and force warm air
between them to rise quickly. Strong
winds and heavy precipitation will occur
Stationary Front

This is the
weather map
symbol for a
stationary front
Warm or cold front stops moving. Light
wind and precipitation may occur across
the front boundary
Reading a weather map

ISOBAR= connects areas of equal
pressure BAR comes from BARometric
pressure
Reading a weather map...

Isotherm: Connects areas of equal
temperature; therm means temperature
Weather Station (not on the TV)