Download Chapter 18-1

Chapter 18 Notes, part I
Date: _______
18.1: The Atmosphere
The atmosphere is a very thin layer (about ______ miles thick) of a variety of gases
surrounding the Earth and is most dense nearest the Earth’s surface. In fact _______% of
all of the molecules in the atmosphere are contained in the 1st _____ miles above sea
level. Two gases make up nearly all of the atmosphere: _______________ (
_________________ (
)--78% and
)--21%. The remaining 1% are mostly the Noble gases (Ar, He, Rn),
carbon dioxide (CO2,--about 0.035-0.037%), water vapor (% varies) and methane (CH4).
The atmosphere is comprised of four distinct layers (p.598, Fig. 18-1):
All weather & life exists in the
____________________. It is the densest
layer and where we live. The
temperature drops about _______ per
km of elevation in this layer.
Temperature __________________
sometimes occur when cool air gets
trapped beneath warm air. This
condition often leads to very bad air
pollution. In the next layer, called the
______________________ the temperature
actually increases as elevation
increases. This is where a very
important chemical, called ___________
(
) is found. This chemical
intercepts UV radiation from the sun
preventing exposure to this very
dangerous energy. Excess UV light can
cause sunburn and worse, skin cancer.
Until recently the ozone in the upper stratosphere was sufficient to protect us from most
of this energy. However, in the 1950’s scientists created a new class of chemicals called
___________________________ (CFC’s) which made for great refrigerants but had a very
nasty, unknown side effect. It turned out that about 10-15 years after escaping from
Earth’s surface these molecules eventually reached the upper stratosphere where they
began to breakdown the ozone. As the ozone began to diminish more UV reached the
surface causing an increase in worldwide skin cancers. It took scientists a while to figure
out it was the CFC’s that were responsible. CFC’s are not made any longer but still the
damage will continue for years as the last of the CFC’s reach the ozone layer.
The coldest of all of the layers of the atmosphere is called the _____________________. This
is also the layer where _________________ (or “______________ _________”) are seen. No life
or travel occurs in this layer. The final layer, called the ________________________ is, as it
name implies, the hottest of all layers. The heat comes from the interaction of all of the
sun’s energy and the outermost portion of the atmosphere absorbing most of that energy
(keep in mind that there are both X-rays and gamma rays in sun light reaching the
Earth!). An interesting region exists between the upper mesosphere and lower
thermosphere which reflects radio waves. This region, called the ___________________
increases in thickness as the sun strikes it throughout the day (causing it to get closer
to the surface); at night it gets thinner, thus moving further from the Earth’s surface.
This rising and falling of the __________________ causes AM radio signals to fluctuate
throughout the day. At night signals travel much further before reflecting. This is why at
night AM stations from 100’s or even 1000’s of miles away can be heard! (Try it using
your car’s AM radio)
Our planet’s earliest atmosphere was very much different than today’s __________________
one. Billions of years ago our atmosphere was loaded with many gases that aren’t in
large amounts today: CO2, CH4, CO, NH3, H2, N2 and H20. This type of atmosphere is
referred to as a ____________________ one. Most of these gases were produced by a
combination of _______________ ________________ and ________________________. Plants
and bacteria would have flourished in this early atmosphere, rapidly producing large
amounts of _______________ while using up CO, CO2 and CH4. This process which so
dramatically changed our atmosphere continued for billions of years. Our current
atmosphere didn’t fully form until “only” ______________________ years ago.
The Earth would be very cold if at night all of the heat gained throughout the day
escaped (the temp would be about _________!). But certain gases in our atmosphere,
particularly CO2, H2O and CH4, absorb much of the infrared energy released back to
space acting somewhat like a clear blanket on our planet.
This process is called the _________________ _______________.
Over the past 200 years the amount of these three gases
(especially carbon dioxide) has increased dramatically, while
at the same time Earth’s temperature is also increasing. The
name “Global Warming” was coined to describe this discovery
in the early 1980’s but recently a new term, ____________ ____________ ____________ has
replaced it as it more correctly describes what scientists are measuring and what we see
occurring across the planet. Reducing the greenhouse gases will play a major role in the
decisions governments and individuals make over the next few decades.
Chapter 18 Notes, part II
Date: _______
18.2: Water & Wind
The ________ _________ is a closed system, no water is ever “lost.”
Important weather (WX) terms;
______________: the measure of ________________ in the atmosphere.
______________ _______________ (RH): the ratio of the amount of water in the atmosphere
divided by the maximum water capacity of the
atmosphere at that temperature (0-100%). Keep in
mind that the warmer the air the ________ water it
can hold.
When RH is low air is “_______;” when RH is high air is “___________.” Human hair is very
sensitive to changes in humidity: as humidity
increases so does hair length (causing a condition
best known as “frizzies”). This observation led to
the invention of a device used to measure humidity:
the _______________________.
______ __________ (d.p.): the temperature at which water vapor starts to condense in to
liquid water. When the _____ __________
temperature is reached ____________ begin to form.
If the d.p. elevation is very low ______ forms.
____________: condensed water vapor. They form when _________, ___________ air rises and
cools. When the d.p. temperature is reached small
water droplets collect. At very high elevation the
temperature is so cold that clouds are likely to be
made of ______ _____________.
There are three main types of clouds (see also p.608, fig. 18-12):
1) high, thin feathery clouds are called __________________
2) sheet-like, layered clouds are called __________________
3) vertically-rising, flat bottom, “pillowy” are called _______________
Clouds are often made of combinations of the above, for example:
high elevation, layered clouds are called ______________________
large vertical, layered clouds are called ________________________
There are two other “root” names:
“middle” elevation is ______________;
“rain” (or low elevation) is _______________
Thus, a middle elevation layered cloud are called _______________________;
Layered rain clouds are called _________________________.
One of the most important WX measurements is _______ (or ___________________)
_________________. The air has some weight. If you were to measure the weight of a 1” x 1”
column of air (some 100 miles tall!) it would be ________ pounds. So the standard air
pressure is _______ lbs/in2 (or ______ ______). The device used to measure air pressure is
called a ___________________. ___________________ measure the pressure as the height a
column of mercury could be raised. Standard pressure would push a column of mercury
___________ inches or __________ mm high. In the US we use inches to measure the air
pressure. It is also very important to remember that _______ air is heavier than _______
air!! Therefore _______ air has greater pressure than _______ air, so:
Chapter 18 Notes, part III
Date: _______
18.2: Weather Symbols
All weather stations show the following conditions:
(1)
Wind speed and direction; wind direction is where it comes from. A south wind
comes from south, so it blows towards the north. Wind speed is shown a symbol
with the wind direction placed around a circle to represent direction and a certain
number of “barbs” or “feathers” representing the wind speed with a change in symbol
every 5 knots:
Speed
Symbol
Speed
0-2 knots
23-27
3-7
28-32
8-12
33-37
13-17
38-42
18-22
43-47
Symbol
(2) Pressure is shown to the upper right of the station symbol, usually in units called
millibars (mb). The typical range in millibars is between 950 and 1040. For
comparison, standard pressure, 14.7 psi = 29.92” = 1013 mb. Only the last two digits
in millibars are shown for clarity’s sake, so a pressure of 82 would be 982 mb and 22
would be 1022 mb. However, we will use inches most of the time in this class.
(3) Temperature is shown in the upper left of the station symbol. In the US we often use
°F for our temperature but °C can be used. In this class we will use °F.
(4) Sky condition is shown in the circle of the station symbol using the following
pattern:
clouds:
So, identify the weather conditions in the following:
14
79
-2
09
A)
B)
C)
state of sky:_______
state of sky: ______
state of sky: ______
wind speed: _______ knots
wind speed: _______ knots
wind speed: _______ knots
wind direction: _________
wind direction: _________
wind direction: _________
temp: ________°C
temp: ________°C
temp: ________°C
pressure: _________mb
pressure: _________mb
pressure: _________mb
____________: the movement of air from an area of _________ pressure to an area of ______
pressure. The _______________ the difference in pressures or the _______________ the
center of pressures, the stronger the ________________ _________________. The device used
to measure wind speed is called an __________________________.
The _______________ Effect: because the Earth rotates winds (and ocean currents) are
affected. In the Northern Hemisphere winds are deflected to the __________ or
________________ direction (opposite in the Southern Hemisphere) When one measures air
movement wind flows __________________ _______ of areas of High pressure and
________________________ __________ areas of Low pressure:
H
L
Circulation Cells and the Earth’s Wind Belts: the __________________ receives the greatest
amount of the sun’s energy. As air gets warmer it expands and rises leaving _______
pressure at the surface. So the equator is an area of _______ pressure. Eventually that
rising air cools and falls back to Earth around _______________ latitude creating an area
of ______ pressure. This area works its way along the surface around 30° north and south
where it rises again, repeating the cycle. Each of these regions on the Earth is associated
with certain climates:
90° N
0°: ____________________________
4
60° N
30°: ___________________________
3
30° N
1
0°
2
30° S
3
90° S
90°: ___________________________
Between each of the world’s
pressure belts are the Earth’s
Wind Belts.
(1) ____________________________
(2) ____________________________
60° S
4
60°: ___________________________
(3) ____________________________
(4) ____________________________
Chapter 18 Notes, part III
Date: _______
18.3: Weather & Climate
____________________ is by definition, the current state of the atmosphere. The
atmosphere is constantly moving (in the Northern Hemisphere it is generally moving
from _________ –––> __________; Why? __________________________________) but sometimes
large quantities of air called ______ __________ become somewhat stationary for a few
days or so. During this time the air begins to pick up the properties of the surface below
it. There are four possible combinations of these air masses depending on whether they
form over land (____________________) or water (___________________) and near the equator
(_________________) or near the poles (________________):
Air Mass
Symbol
Conditions
Forms Over
1
2
3
4
Weather Fronts
Weather fronts are boundaries between two different air masses, one warm and one cold.
At the boundary storms can occur. The are four different type of frontal boundaries:
(1) _________ front: during these a warm air mass meets an existing cold air mass and
rises over it (since warm air is less dense). A progression of clouds develops before the
storm begins:
Rain forms near the _______ of the passing warm front. Warm front storms are
usually less intense with rain lasting a period of ________________. The symbol
used on weather maps to show warm fronts is a series of red semicircles:
(2) __________ front: during these a cold air mass meets an existing warm air mass. Since
cold air is more dense the cold front wedges under the warm air causing the warm air to
rapidly rise:
Cold front storms are usually very brief but can be very intense.
______________________ are common due to the presence of CN clouds. Sleet and
hail are also common in many areas. The symbol is a series of blue triangles:
(3) __________________ front: these occur when a warm front and a cold front “slide” past
each other, traveling in opposite directions:
Along the boundary there is little to no clouds because the different air does not
mix much. Any precipitation is small and short-lived. The symbol is a series of
alternating red semicircles and blue triangles on opposite sides:
(4) _________________ front: these occur when a cold front catches up to a moving warm
front. Very strong storms occur at the boundary. ___________________ can occur due to
the large differences in energies and the dramatic ________________ and rapidly
_______________ clouds. Note: the weather map symbol is usually purple! (Why?)
Chapter 18 Notes, part IV
Date: _______
18.3: Severe Storms
(1)____________________ form when warm moist air is forced to rise in areas of cold,
________________ air:
(2) Lightning and Thunder: Lightning is “just” a discharge of _____________________ which
occurs in T-storms. They can be of three different types: _________ to _________ (
__________ to ______ (
) or ___________ to _____________ (
),
). The temperature of
lightning is about ____________ °C (or about ____ times hotter than the surface of the
sun!) When air heats this much so rapidly it expands explosively producing a
______________ called ______________ that travels outward in all directions. Remember:
______________ ____________ _____________. If you count the number of seconds between
the lightning flash and the thunder clap and divide by 5 you get an approximate distance
of the lightning in miles. So if 10 seconds takes place between the two the lightning is
about 2 miles away.
(3) When the difference between the
(–) bottom of the cloud and the (+)
surface of the Earth becomes large
enough ( about ______________ volts
per meter!) current flows and
lightning is created.
(3) __________________: rapidly rotating winds that blow around an area of intense ______
pressure. They start as a _____________ __________ which eventually might touch the
ground (only then does it become a tornado). The largest number of tornadoes occur in
the _____________ ____________ of the United States (called ____________ ___________)
during the months of _________ to __________. Tornadoes have winds between 40 mph
(classified as ______ on the Fujita Scale) to over 300 mph (an ______). Tornadoes form
when ______ air mixes with _______ during _________________ fronts:
(4) ________________: these are huge thunderstorms that start out over land near the
equator and move over _______ ocean water. Large amounts of ____________ clouds (so
__________ air) and humidity quickly develop. They are called ________________ in the
western Pacific (Japan, China) and ______________ in Australia and India. Hurricanes are
usually between _______ and _______ miles in diameter and are noted for very low
pressure in the center (as low as _______ but average around ________). The actual center,
called the _____ is very calm but spiraling outward are winds which must exceed _______
mph (called a _______________ hurricane) to more than _________mph (a
_________________). There is a progression of events leading up to a hurricane:
(1)_____________________
(2)__________________________
(3)__________________________ (this is when a storm first gets named)
(4)____________________
Every year a new set of names are listed in alphabetical order, alternating male and
female names. If a hurricane is particularly damaging the name is forever retired
(Andrew, Camille, Katrina to name a few).
Hurricanes form in a region near the equator called the _________ ______________
_________________
________ (
).
(1) As the hurricane moves from the equator it gathers strength over _________ water as it
continues to move slowly ( about ____ to ____ mph) towards the ________.
(2) Once the hurricane leaves the _________ it begins to encounter the prevailing
__________________ winds and begins to move towards the _________, often out of harm’s
way. However this does not always happen and some hurricanes make landfall and cause
destruction.
(3) Most damage from a hurricane comes not from the winds but from the __________
_________, a large mass of ocean water caused by the very low pressure center. Often the
storm surge can be ____________ feet tall when the storm comes ashore!
Chapter 18 Notes, part V
Date: _______
Last of Chapter 18
The Earth’s Tilt & the Seasons
While the Earth orbits (goes around ) the sun it does so not with its axis of rotation
(the “poles”) perpendicular to the orbital plane but rather tilted at an angle of _______.
Since the Earth can tilt towards the sun, away from the sun, or some angle in between,
the amount of sunlight a given location receives varies throughout the year. The sun is
directly overhead at “_______” at the equator only twice a year: on the first day of spring
(called the ___________ ______________), around _________, and the first day of fall (the
______________ _________________), around _________. From the first day of spring to the
first day of summer (called the _____________ ______________) around __________, the sun
rises higher each day above the equator (further __________). On the first day of summer
the sun is as high in the sky it will be throughout the year and will cover the greatest arc
so the amount of daylight is _____________ on this date.
On the first day of Spring at the North Pole the sun just peaks over the horizon and
now starts a 6 month stay in the sky! Each day after this the sun will not set all day
even further south until on the first day of summer the sun will stay above the horizon
at its southernmost spot for 24 hours: called the ___________ ___________. Its latitude can
be found by subtracting the tilt of the Earth from the latitude of the North Pole, so its
latitude is ______ (
). After the Summer Solstice the sun begins to rise lower in
the sky (further south), crossing the equator on the autumnal equinox and continuing
further south until the first day of winter (called the _____________ ______________)
around __________. This day marks the lowest point the sun reaches in the sky. On this
date the sun does not rise above the horizon at the Arctic Circle so on the first day of
Winter the Arctic Circle gets no sunlight! Between the first day of fall and the first day of
spring the North Pole receives no sunlight.
Keep in mind that everything is the opposite in the southern hemisphere: our winter
is their summer, our fall is their spring; so on March 21st the South Pole enters 6
months of ______________ and on June 21st the ____________________ circle experiences 24
hours of _________________.
_______________: the average weather conditions of a region over many years. The three
main factors of _______________ include ________________ (features such as mountains,
valleys, proximity to oceans and lakes, elevation), ________________ (relationship to
equator, H and L pressure belts) and ___________________ (note in the world map below
the difference between the amount of land mass North and South of the equator!)
Ocean Currents in the Northern Hemisphere
Water, like the atmosphere, is driven by the Coriolis Effect so in the Northern
Hemisphere ocean currents rotate to the right (clockwise). The equator is the location of
very warm water where the poles are regions of cold water, therefore water flows from the
________________ to the _______________. Since the water flows northward from the
equator on the __________ side of the ocean the _________ coast of continents are usually
more ________ and the _________ coast of continents are usually less _________.
The Bay Area’s climate is very similar to that of Italy, Spain & France and is called a
________________________ climate. The reasons:
1)
2)
Upwelling
Upwelling occurs when ocean breezes cause water to move ________ from the coast. As
the water moves ________ colder water from below rises to the surface to take its place.
This colder water contains much more dissolved nutrients and oxygen which in turn
makes the region more beneficial for aquatic life especially __________________________.
Along the equator the trade winds normally push the surface water towards the west
causing upwelling at the eastern side of the ocean. Of the coast of ________, in South
America fishermen welcome this condition as it brings tremendous amounts of fish to
the coastline often very near the surface. There is a time when the trade winds weaken
and instead of cold water near the coast of Peru there can be large amounts of warm
water.
This event is given the name ____ _________ since it often occurs around
_________________. Along with warm water off the Peruvian coast more warm water gets
“pushed” North and South of the equator creating ______________ amounts of rainfall on
the west coasts and affecting the overall weather patterns for large areas. The opposite
effect, called ____ _____________ can cause _______________ over large regions. The name
given to this shifting of the surface water temperature from west to east is called ________
(____ __________ ________________ ________________________). Scientists can forecast the
amount of ________ by mapping out the surface temperature of the ocean water near the
equator. This year scientist predicted a _______% ____ __________. What does this mean
for us in California? _______________________________________.