Exam 2 Chap8

Question 1

This exist whenever air pressure varies between locations
it also can be measured in direction of greatest change
also travels perpendicular to isobars

Answer 1

air pressure gradient

there are two types horizontal (more common) and vertical pressure gradient

Question 2

What happens with closely spaced isobars?

Answer 2

air pressure changes rapidly with distance
strong pressure gradient
stronger winds blows from high to low pressure

Question 3

What happens with widely spaced isobars?

Answer 3

air pressure changes gradually with distance
weaker pressure gradient
high pressure at the bottom but low at the top, will blow slower than closely spaced isobars

Question 4

What is the centripetal force?

Answer 4

Center seeking force,
affects winds on a curved path
force directed perpendicular to direction of object’s motion, toward center of circular orbit
Relevant for winds that are blowing on a curved path

Question 5

What is the coriolis effect ?

Answer 5

not a true force but an effect, apparent deflected motion of object to the right northern hemisphere
stronger at the poles, weakest at the equator
influences the wind in large scale weather systems

Question 6

This is resistance an object as it moves in contact with another object or medium

Answer 6

friction happens in the boundary layer in the atmosphere
it slows down winds closer to the earth’s surface
creates turbulence

Question 7

force that holds objects to the earth’s surface

Answer 7

Gravity only influences ascending or descending air

Question 8

hydrostatic equiplibrium is ?

Answer 8

the balance between the force of gravity pulling an air parcel down towards the earths surface vs. the vertical pressure gradient that wants to pull the air parcel up in the atmosphere; these two forces are balanced so the air parcel stays right where it is

Question 9

horizontal movement of air (No curvature here) that follows a straight path at altitudes above the atmospheric boundary layer (away from the earth’s surface where there is frictions)

Answer 9

the geostrophic Wind

Question 10

Geostrophic wind also

Answer 10

wants winds to blow from high pressure to low pressure
there are two things at play the coriolis effect and the horizontal pressure gradient…
HPG wants the air parcel to go up but the coriolis pulls the movement to the right the longer the trajectory the longer the coriolis effect is going to be.
When both reach equilibrium the air parcel will be parallel to the isobars

Question 11

This wind is similar to the geostrophic wind in that it is up out of the boundary layer and no friction is coming in to play. this time we are looking at a curved path so another force kicks in which is the centripetal force..

Answer 11

Gradient wind it occurs around high and low pressure centers above the boundary layer…moves counterclock wise in the northern hemisphere —

Question 12

What are surface winds like

Answer 12

friction combines with the coriolis effect to balance the horizontal pressure gradient force….friction acts directly opposite the wind direction. The coriolis effect always at the right angle to wind direction .
-Winds cross isobars at an angle that depends on roughness of earth’s surface

Question 13

High pressure cell surface winds

Answer 13

clockwise and out in the northern hemisphere
decreases as it moves out
-anti cylone

Question 14

low pressure cell surface winds

Answer 14

counter- clockwise and in northern hemisphere
wind moving in this direction are defected to the right (c effect)
-cyclone

Question 15

Forces change with altitude

Answer 15

the closer to earths surface the winds are, the more friction comes into play
for the same horizontal air pressure gradient the angle between the wind direction and isobars decrease with altitude in the atmospheric boundary layer.

Question 16

With isobars when do winds blow the hardest?

Answer 16

When the lines are tightly packed and vice vera

Question 17

When a ridge occurs on a weather maps what has happened

Answer 17

there has been a bit of curvature around high pressure cells

Question 18

Troughs occur where on the weather map?

Answer 18

low pressure cells

Question 19

The gradient wind follows (parallels) curved isobars whereas the geostrophic wind follows
straight isobars. Both are horizontal and occur above the atmospheric boundary layer where
frictional forces are essentially absent.

Answer 19

Distinguish between the geostrophic wind and the gradient wind

Question 20

Upper-air support for a developing cyclone requires horizontal divergence. Explain why

Answer 20

Horizontal divergence aloft allows converging air at the surface to rise.

Question 21

In view of Newton’s first law of motion, is the gradient wind a consequence of balanced
forces? Explain your answer.

Answer 21

No. The gradient wind is not the consequence of balanced forces because the gradient wind is
curved motion rather than straight-line motion. According to Newton’s first law of motion, a net
force must operate to cause air to move in a curved path as viewed from above.

Question 22

What is hydrostatic equilibrium? Is vertical motion of air possible with hydrostatic
equilibrium? Explain your answer.

Answer 22

Hydrostatic equilibrium is a balance between the vertical pressure gradient force and gravity.
Vertical motion is possible with hydrostatic equilibrium, however, particles will move at a
constant velocity