ATMO 170
Optional Assignment
Name_______________________________
1.
Does the figure show SURFACE or UPPER-LEVEL
winds? Are they blowing around a center of HIGH
or LOW pressure? Are these SOUTHERN or
NORTHERN hemisphere winds?
Surface winds blow across the contours always toward low
pressure (upper level winds blow parallel to the contours, kind
of like what the winds in question #5 are starting to do). To figure out the hemisphere
you can imagine you are approaching the picture from the south and want to merge with
the existing winds. You would have to take a left turn as you approached the center of
low pressure in order to end up traveling clockwise around the low. The left turn is
telling you this is a southern hemisphere chart (the left turn is caused by the Coriolis
force which is always perpendicular to the wind, to the right in the northern hemisphere
& to the left in the southern hemisphere.)
2.
You observe a large storm system on a satellite photograph that is moving from east to
west and spinning in a clockwise direction. This would most likely be a (circle 3 choices
below, one from each column)
Northern hemisphere
middle latitude
anticyclone
Southern hemisphere
tropical
cyclone
The thing I would suggest you do is to look at the first figure in the Tuesday, Nov. 12
lecture notes. A variety of storm systems are shown. At middle latitudes (30o to 60o
latitude) you find middle latitude storms or extratropical cyclones. Hurricanes or tropical
cyclones are shown between 0o to 30o latitude (the tropics and subtropics). The winds in
all cases are spinning around low pressure, these are all cyclones. Middle latitude storms
move from west to east, tropical cyclones move from east to west. Winds spin clockwise
around low pressure in the southern hemisphere.
3.
Which figure shows winds blowing in the southern
hemisphere? (CF shows the direction of the Coriolis force)
CF is perpendicular and to the left of the wind in the
southern hemisphere (remember you must be looking
in the direction of the wind, looking downstream)
4.
Isaac Newton
a. invented calculus b. formulated a law of gravitation
c. formulated laws of motion
d. discovered that when white light shines through a glass prism it is split into colors
e. all of the above
5.
The direction of the initial motion in the figure at right
means this is a center of HIGH LOW pressure. Rather
than going straight toward the center of the picture the
wind turns to the left. The direction of this bending
means that this is a NORTHERN SOUTHERN
hemisphere chart.
Just like a rock will start to roll downhill, the initial motion of air is always in the
direction of low pressure (the PGF is what can cause stationary air to start to move and
the PGF always points toward low pressure). The CF is what then causes the air to take
the left turn and CF acts to the left of the wind in the southern hemisphere.
6.
The direction of the ______ force changes when you move from the northern to the
southern hemisphere.
a. Coriolis
b. frictional
c. gravitational
d. pressure gradient
7.
At the point shown in the figure at right,
the pressure gradient force (PGF) will point
toward the ___SW__ in the northern hemisphere
and toward the ___SW____ in the southern hemisphere.
(fill in each blank with NE, NW, SE, or SW)
The rule for PGF is that the PGF is perpendicular to the
contours and points toward Low. There's nothing in the
rule that depends on what hemisphere you're in.
8.
Have you ever been to the southern hemisphere? If so, where?
While the majority of students hadn't yet been to the southern hemisphere a number had
and to a wide variety of countries.
9.
The term __________monsoon_____________ refers to a seasonal change in the
direction of the prevailing winds.
9.
The speeds of 5 upward or downward moving
objects are shown at right. From careful study
of the object’s motions and making use of
Newton’s 1st law of motion, you could conclude
that there is no net force acting on the objects in
___a___ and ____e___. An upward force is
being exerted on the object in ___d___. A
downward force is acting on the object in
___b____ and ___c___.
Most everyone realized the straight line motion at constant speed in (a) and (e) indicated
zero net force. If you throw an object upward gravity will slow it down (as shown in (b)),
cause it to stop, and then cause it to start to fall back to the ground picking up speed as it
falls (as shown in (c)). Gravity points downward, so a downward force is present in (b)
and (c). That leaves (d) as the only example where an upward force is present.
10.
The direction of the PGF in the figure at right
tells you that this is a center of HIGH LOW
pressure. The direction of the CF is to the
RIGHT LEFT of the wind (as you look downstream
which indicates this is a SOUTHERN NORTHERN
hemisphere chart.
11.
Rising air motions are produced by surface centers of HIGH LOW pressure in the
northern hemisphere and centers of HIGH LOW pressure in the southern hemisphere.
See the discussion for Question #1. Convergence is what causes the air to rise. Surface
winds spiral inward (converge) around surface centers of low pressure. It doesn't matter
what hemisphere you're in.
12.
The wind is blowing in a circular path at constant
speed in the two figures at right. The direction
of the net force is
a. inward around L, outward around H
b. inward in both figures
c. in the direction of motion in both figures
d. zero in both figures
13.
The strength of the ___a___ force and the ___b___force depend on wind speed.
a. Coriolis
b. frictional c. gravitational
d. pressure gradient force
14.
Identify the three forces in the figure at right.
Does this shown SURFACE or UPPER LEVEL
winds. Are these NORTHERN or SOUTHERN
hemisphere winds. Is low pressure found at the
TOP or BOTTOM of the figure
The upward pointing force is the PGF. The PGF
always points toward low pressure, so low pressure is at the top of the picture. The
frictional force is pointing opposite the wind, toward the lower right corner of the figure.
The 3rd force, pointing toward the bottom left of the figure in the CF. Note it is
perpendicular and to the left of the wind indicating this is a southern hemisphere map.
The wind is blowing across the contours (indicating a surface wind).