Exam 2

Question 1

What is a surface weather map? What is the correction factor that is used to draw it?

Answer 1

Plot of pressure values at sea level that have been corrected for altitude variations
Correction factor = 10 mb for every 100 m (328 ft.) in altitude

Question 2

What is an Isobaric weather map? What is the name of the isobaric chart halfway up in the troposphere?

Answer 2

A map with constant pressure, not altitude.

Halfway up is the 500mb level chart.

Question 3

What causes changes in Geopotential height contours? Draw a sketch showing two column of air –one warm and one cold illustrating the changes.

Answer 3

Temperature

see #52

Question 4

When an isobaric surface is non- uniform or wavy what are two features that typically show up on an isobaric chart? What are their corresponding pressures?

Answer 4

Troughs and ridges. Low = trough. High = ridge

Question 5

What are three measurements that are typically given on an Isobaric Chart?

Answer 5

Temperature, dewpoint, height, windspeed, wind direction

Question 6

What are 3 forces that influence the direction of the wind?

Answer 6

Pressure gradient force, Coriolis force, Centripetal Force, Friction Force

Question 7

What is the Coriolis force and why does it occur on Earth? What direction does it deflect the wind in the Northern Hemisphere? How does it change with wind velocity?

Answer 7

A “fictional” force that causes the wind to change direction due to the rotation of the Earth. The wind is deflected to the right in the northern hemisphere.
As wind velocity increases, so does the Coriolis force.

Question 8

On an upper air chart what direction is the wind relative to the contour lines that are evenly spaced? What type of wind is this called? Draw a sketch.

Answer 8

The wind is going parallel to the contour lines.
Geostrophic winds.

(#57)

Question 9

What is the Planetary Boundary Layer (PBL)?

Answer 9

The lowest layer in the Troposphere and its behavior is directly influenced by the Earth’s surface.

Question 10

How does friction influence the wind – name two properties?

Answer 10

Wind speed generally increases with an increase in altitude because it is less affected by friction by objects on the Earth’s surface

Properties:
Distribution of Sea Level Pressure
Air rotates CCW into the large Low Pressure (cyclone) over the central US.
Winds are weaker out of the High Pressure (anti-cyclone) in the West

Question 11

Draw a sketch of a cold and warm column or air. Why is a colder column shorter?

Answer 11

61

Question 12

What is the value of the 1000-500 mb height that is considered the rain/snow line?

Answer 12

5400m

Question 13

What is the definition of Advection? Give one example

Answer 13

Horizontal change of a property. Ex: Temperature advection means a temperature is changing horizontally.

Question 14

Names three weather forecasting parameters that can be obtained from the 850 mb map.

Answer 14

High temperature, cloud formation, wind speed

Question 15

What is vertical velocity? At what height (mb) is usually measured. A negative value of vertical velocity indicates what type of surface weather might occur?

Answer 15

Vertical velocity is the speed at which the air is rising or sinking. Measured at the 700mb level. A negative value indicates rising air.

Question 16

What does the term “digging” refer to in a weather forecast?

Answer 16

Digging is when surface pressure of the low is decreasing over time within the center of the low

Question 17

What is a cut-off low? Draw a sketch.

Answer 17

67

A low that is cutoff from the main steering winds. It ends up just sitting there, delivering rain for days.

Question 18

What is vorticity? What level of the atmosphere (mb) is it usually measured? High vorticity usually indicates what type of surface weather?

Answer 18

Spin in the atmosphere. 500mb. More positive vorticity ( strength ) = divergence = more chance of a severe storm

Question 19

What is a jet streak? What is its typical speed? What type of surface weather is associated with a jet streak?

Answer 19

Jet streaks are segments of faster wind speed within the jet stream. 160 knots ( 184 mph). Associated with development of surface low pressures and mid latitude cyclones

Question 20

What is the definition of Wind? How does it impact our Weather?

Answer 20

Movement of air horizontally due to pressure differences (low to high). but is influenced by other forces, Cariolis, centripetal, and friction
Wind moves weather systems.

Question 21

Draw a sketch showing the origin of Lake Effect Snow. Include surface convergence and divergence and the resultant flow to the upper atmosphere.

Answer 21

71

Question 22

What is the definition of a Prevailing wind? Explain how it could influence home building in the NE United States.

Answer 22

Wind direction most often observed during a given period of time. It is best to build homes with windows facing southwest for ventilation in the summer.

Question 23

What are the 4 Scales of Motion in the atmosphere and give one example of each.

Answer 23

Microscale - Wind at the surface-2m (paper blowing on the surface)

Mesoscale - Size of a city - thunderstorm

Synoptic scale - (About size of U.S.) - tropical storms

Global/Planettry scale - Trade winds

Question 24

What is an Eddy? What are the two types and what are they caused by?

Answer 24

Small chaotic motions
Example: Air pocket when on a plane

Mechanical Turbulence -
Caused by Obstructions

Thermal Turbulence -
Caused by convection or rising thermals of air

Question 25

What is a thermal circulation? Give two examples.

Answer 25

A circulation generated by pressure gradients that are caused bydifferential heating
Ex: Sea and land breezes
Monsoons

Question 26

Why are there many thunderstorms in Florida in the afternoon?

Answer 26

Converging Sea Breezes produce lift -> RECC

Question 27

What is a Chinook Wind? Where are they typically found? Why are they called Snow Eaters?

Answer 27

Warm, dry downslope wind
Usually found on Eastern slopes of the Rockies ( US and Canada)
Differs from Katabatic because of rain shadow on windward side
Snow Eaters cuz
They are thirsty winds (very dry) and very warm since they heat up as they travel down slope ( SCWE ; sinks, contracts warms and evaporates)

Question 28

What are Santa Anna winds? What surface weather condition is required to form these winds. What natural disaster can be a result of these winds?

Answer 28

Hot, dry winds that often sweep through the L.A. Basin in the fall and winter.Air parcels become warmer and drier due to compressional heating. When L.A. is dry due to drought, forest fires usually are a result of these winds

Question 29

What are the names of 3 global circulations?

Answer 29

Jet stream
Gyres
El Nino/ La Nina

Question 30

Draw a sketch of the cells predicted by the 3-cell model in the Northern Hemisphere . Label the cells with their names. Include latitudes and show circulations

Answer 30

81

Question 31

Draw a sketch and show the 4 surface highs and low in the Northern Hemisphere. Label each one with a H or L and include the name. Classify the lows and high pressures predicted by the 3 cell model according to how they are formed.

Answer 31

82

Don’t forget: Subsidence, thermal, thermal, lift
Thermal           90
Lift		       	60
Subsidence      30
Thermal 		0

Question 32

What are three predictions of the 3-cell model?

Answer 32

ITCZ, Jet Streams, Doldrums, Subtropical Highs, Easterly Trade Winds, Polar Front, etc

Question 33

Why are most of the major deserts of the world located at 30 deg latitude?

Answer 33

Since at that 30 degree mark you get dry, sinking air. (High pressure). Subsidence.

Question 34

What does ITCZ stand for? What type of weather is typically found at the ITCZ? Why?

Answer 34

Inter tropical convergence zone. High amounts of precipitation/thunderstorms. This is due to converging winds and the low pressure over that area.

Question 35

How does the position of the ITCZ change in the summer and winter season? What major weather event is associated with this change?

Answer 35

Shift North in Summer and South in the winter

Monsoons

Question 36

What are the names of the semi permanent Highs (one in the Atlantic and one in Pacific Ocean) that influenced weather in the NE and California? How do they influence the weather in the summer Include their location.

Answer 36

Pacific High moves northward in Summer. Keeps summers dry along west coast. Winds from northwest

Bermuda High - brings warm humid air to the east coast .Thunderstorms are common. Winds from gulf of mexico

Question 37

What is the origin of the Jet Stream?

Answer 37

Steep temperature gradients -> strong wind -> pressure gradient force -> Coriolas pushes them west

Question 38

What are the names of the two Jet Streams in North American. What latitude are they located at? Which direction do they flow?

Answer 38

Polar (60 degrees N) and subtropical (30 degrees N)

Question 39

What is a Jet Streak? How does it influence the weather at the surface?

Answer 39

Localized regions of very fast winds embedded within the jet stream. Storms are formed at the end of a jet streak (low pressure).

Question 40

What are three ways that the Jet Streams influence our weather?

Answer 40

• Transport of Heat Energy Poleward
• Influence surface temperature (trough means cold air moving in)
• Guide Mid Latitude Cyclone Storms

Question 41

What is a Monsoon? What causes it to occur?

Answer 41

A name given to seasonal winds that typically blow form different directions during different times of the year, usually summer and winter. Due to shifting ITCZ band.

Question 42

What is a Gyre? What is the name of the Gyre that flows near the coast of North Carolina? How does it affect the weather in England and Norway’s coast?

Answer 42

A large system of circulation ocean currents (formed by global wind patterns and forces created by Earth’s rotation).Gulf Stream flows near North Carolina. Brings heat up to England and Norway’s coast.