Air Pressure and Winds
What is a gradient? Provide an example.
Change in a quantity over a distance.
Example: change in air pressure over a distance.
What causes eddies?
Obstructions
What is the underlying cause for the movement of air?
energy imbalance (receive different amounts of insolation)
What is a weather front?
Where two air masses collide
Describe at least 3 components of the global observing system
Land weather stations, buoys, commercial aircraft data, ships, radiosondes, dropsondes, Doppler Raders, satellites, etc.
Lines of equal pressure on a map are called...
isobars
Which direction are winds deflected in each hemisphere?
Winds are deflected to the RIGHT in the northern hemisphere and to the LEFT in the southern hemisphere.
Draw and label the three cells on the globe.
0-30 degrees - Hadley Cell
30-60 degrees - Ferrell Cell
60-90 degrees - Polar Cell
Which type of front is most likely to have cumulonimbus clouds and thunderstorms?
cold front
Describe how a basic numerical weather model works
Divide atmosphere into grid cells, feed in current weather data, use equations to see how cells change in the future
What three forces act on air and make it move?
Pressure Gradient Force
Coriolis Force
Friction
Explain the formation of sea breezes.
Land heats faster than water, is relatively warmer, so air rises above land, creating LOW pressure zone. Air moves from HIGH over water to LOW over land.
What is the ITCZ? Where is it located?
Intertropical Convergence Zone
Located near the equator, shifts north or south seasonally
Which type of front is most likely to have drizzle and precipitation far in advance of the front?
warm front
What is the difference between a watch, a warning, and an advisory?
ADVISORY issued for less hazardous weather, such as wind, fog, or snow
WATCH issued when atmospheric conditions favor hazardous weather
WARNING issued when hazardous weather is imminent or occurring
At the surface, is air rising or sinking at a low pressure zone? At a high pressure zone?
Rising at low pressure
sinking at high pressure
What causes monsoons and why are they important?
Seasonal changes in wind direction caused by differential heating of land and water (like sea breezes and land breezes).
Provide most of precipitation for some areas.
Draw and label the prevailing winds in each circulation cell.
SE and NE trade winds, westerlies, polar easterlies
What is the difference between cold and warm fronts in terms of speed, shape, and types of clouds and precipitation?
Cold fronts are steeper, move faster, and have tall clouds and thunderstorms
Describe an ensemble forecast and why it is useful
Run multiple models, where they converge, you can be more confident in the forecast
Describe how the magnitude of the Coriolis forces changes with (1) latitude and (2) speed.
Coriolis increases with both latitude and wind speed.
What are two other names for Chinook Winds? Why are they sometimes dangerous?
Santa Ana, Foehn, Zonda, Loo
Can dry out fuel and quickly spread wildfires
What is ENSO? How is related to the trade winds?
El Nino Southern Oscillation
Weakening of trade winds, equatorial Pacific water "sloshes" back towards S. America, changes global weather
Sketch the three phases of a mid-latitude cyclone
stationary, open wave, occlusion
What are 3 things that cause Variation in Models and Limitations in Forecasts
Assumptions about behavior (equations used)
Initial conditions (data going in)
Grid spacing (terrain details, ice, water cover, etc.)