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24 Cards in this Set
- Front
- Back
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Name the four scales of motion and give an
example of each. |
1) Microscale → eddies, downburst
(microburst) 2) Mesoscale → thunderstorms, land and sea breeze 3) Synoptic scale → low and high pressure systems, weather fronts 4) Global (Planetary) scale → jet stream, long wave trough and ridges |
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What causes wind gusts?
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Wind flowing over irregular shaped objects, twisting eddies inluence air flow.
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What is the height of the ‘planetary
boundary’ or ‘friction’ layer”? |
1000 m (3,330 ft) AGL
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Why are winds near the surface typically
stronger and more gusty in the afternoon? |
Heating in the afternoon increases earth instabilty in lower levels of the atmosphere. This causes exchange of faster moving air from upper levels with slower
moving air at lower levels. |
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What three factors contribute to the depth of
mixing and, hence, frictional influence in the planetary boundary (friction) layer? |
1) Surface heating → produce a steep lapse
rate and strong thermal turbulence 2) Strong wind speeds → produce strong mechanical turbulent motions 3) Rough or hilly landscape → produce strong mechanical turbulence |
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Clear air turbulance
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Wind shear creates forces that produce eddies within a mixing zone. On top of the mixing zone you will have strong winds and on the bottom lighter winds. If the eddies form in clear air.
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Explain how shelterbelts protect crops from
wind damage. |
Shelterbelts consist of a mix of conifer and
deciduous trees that are planted in rows perpendicular to the prevailing wind flow. The shelterbelt will cause the wind flow blowing through them to break down |
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What three factors determine the height of
“wind created waves” over a body of water? |
1) The wind speed
2) The length of time that the wind blows over the water 3) The fetch, or distance, of water over which the wind blows. |
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How can a coastal area have heavy waves
which cause beach erosion on a clear, non-stormy day? |
A stationary storm system can create waves up too 50-100ft. As it travels energy is lost when it is broken onto the shorelines.
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If you are standing directly south of a smoke
stack and the wind from the stack is blowing over your head, what would be the wind direction? |
North, winds named from where they came.
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Wind direction - 310 Degrees
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Northwest
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Indentify winds that are affected by interaction with land vs. water or terrain.
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Onshore wind→ wind blowing from water
onto land Offshore wind→ wind blowing from land to water Upslope wind → air moving uphill Downslope wind → air moving downhill |
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What is a “prevailing wind”? What is the
prevailing wind in the state of North Dakota |
Most oberved wind direction in the period of over a year.
North Dakota's is Northwest. |
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Explain how a thermal circulation develops.
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produced by the heating and cooling of the atmosphere near the ground.
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Where can thermal circulation affect weather
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The development of the land and sea breeze
across the state of Florida during the summer months |
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What is the difference between a “valley” and
“mountain” breeze? When do they form? |
A valley breeze is a gently upslope wind while a
mountain breeze is a gently downslope wind. |
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What is a “monsoon”? Where is the best
know monsoon in the world? Does any location in the U.S. experience a monsoon? |
A monsoon is a wind that changes direction
seasonally. The best known monsoon occurs in India. The winters are dry due to a northerly wind and the summers are wet due to a southerly wind. No area in the US experiences monsoon. |
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Why are Chinook winds dry and dry down sloping wind?
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Warming occurs when latent heat of
condensation is added to a rising parcel of saturated air on the windward side of a mountain. |
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Why are Chinook Winds dry?
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Moisture is removed from the parcel on the
windward side of the mountain when precipitation falls out of the parcel as rain or snow. |
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Where you expect chinook winds in the US.
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Front range or leeward side of the Rocky Mountains.
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What is a ‘katabatic’ wind ?
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This is a Cold down sloping wind and develops when cold air develops on a high plateau.
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What is a Santa Anna Wind?
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Winds descending from an elevated desert plateau affecting Southern California. Due to compression.
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What is a Dust Devil and how do they form?
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Spinning vortices due to dust, sand, and dirt in the air. Form on clear hot days due to the surface air becoming super- adiabic and starts to rise rapidly. Air aloft isunstable allowing the heated surface air to
rise to a higher height. |
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What are three instruments that measure wind direction and/or speed?
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1) Wind vane → determines wind direction
- Arrow with tail, wind sock 2) Anemometer → measures wind speed - Cup, pressure plate, sonic 3) Aerovane → measures wind direction and speed - Combines wind vane and anemometer into one instrument. |
