Homework Questions for Lecture 18
ES 1000
Use these questions to test your knowledge of Lecture 18 and related reading on weather. There is a very important weather problem on the sea breeze at the end, part F. Be sure you do it.
1) Density decreases with increasing (choose: attitude / altitude/ albedo) Pressure is caused by impacts; low altitude dense air has more molecules, more impacts and so greater pressure.
2) An air mass develops when the atmosphere is located above a uniform surface for several ______.
3) North American Weather is dominated by ______(cP) and ______(mT) air masses.
4) Continental air masses are found over _____, maritime air masses over ocean.
5) Orographic Lifting forces maritime mP and mT air masses upward over mountain ranges in the western U.S., leading to condensation and precipitation that converts the formerly humid air to a much _____ air mass.
6) ____-______Cyclones up to 2,000 km across effect the weather of the US and Eurasia for three days to a week.
7) Supercells may drop severe hail and may spawn ______.
8) A strong tornado often is associated with rapid removal of updraft air by the _____ Stream aloft.
9) When extremely hot ocean surface temperatures (>26oC) cause hot, moist surface air, huge clusters of thunderstorms develop at sea. If uplift gets extreme, these can organize into a gigantic Low with spiral storm lines and winds exceeding 72 mph, called a ______
B. Matching.
1. Front _____ a. Mid-Latitude Cyclone 2000 km lasts 3 days
2. Hadley Cell _____ b. second most frequent weather-related killer
3. Lightning _____ c. line of storms from rising equatorial air
4. ITCZ ____ d. boundary between contrasting air masses
5. Synoptic scale____ e. drops dried air on +/- 30o Latitude
C. True and False. Please CIRCLE the correct answer.
1. In the Northern Hemisphere, winds circulate clockwise (CW) around a Low pressure area. True or False?
2. Near the Equator, hot moist air rises at the Intertropical Convergence Zone (ITCZ). The uplift starts the Hadley Cells that deliver dry air to subtropical latitudes. True or False?
3. Cumulonimbus clouds (Thunderstorms) are partly in front of an advancing cold front, and are caused by the lifting of warm moist air by the advancing cold front wedge. True or False?
4. Warm front rain may last longer than for a cold front because the warm front moves slowly and extends over a larger area. True or False?
5. Expect decreasing temperature and humidity and increasing atmospheric pressure with the passage of the cold front. True or False?
6. Warm air will always rise over cooler air so both the cold and warm fronts are inclined toward the warm air mass. True or False?
7. A cold front is faster than a warm front and will eventually close the gap between them, forcing the intervening warm air upward generating additional rain. An occluded front results. True or False?
8. Surface Lows move toward upper level convergence. True or False?
9. Condensation occurs as moist air cools, releasing latent heat and ensuring that the rising air remains unstable (warmer than surrounding air). True or False?
10. Doppler Radar can be used to identify possible tornadoes by looking for hook shapes with opposite direction flow on near and far sides. True or False?
11. Hurricanes are fueled by the release of Latent Heat of Condensation. True or False?
D. Multiple Choice. Please CIRCLE the correct letter.
1) Advance warning of a Warm Front is the cloud sequence:
a) Cirrus, cirrostratus. altostratus, nimbostratus
b) altostratus, nimbostratus, cirrus, cirrostratus
c) cirrostratus. altostratus , nimbostratus, cirrus
d) nimbostratus, altostratus, cirrus, cirrostratus
2) Of the following, an acceptable NWS weather station location would be:
a) a building roof next to the air conditioner vents
b) a parking lot
c) adjacent to a busy road
d) an isolated field
3) A barometer measures:
a) Temperature
b) Pressure
c) Humidity
d) Wind Speed
4) An anemometer measures:
a) Temperature
b) Pressure
c) Humidity
d) Wind Speed
5) One day of Latent Heat of Condensation release in a hurricane is about equal to:
a) The energy needed to light a large office building for a day
b) The energy used by a small town for a week
c) The energy used by a large city for a month
d) The energy used by the US for a year
E. Short answers. This homework question is similar to the last, because these topics, and the next question, are the crux of this third of the course.
BE SURE YOU DO THIS
Discuss rising air. Be sure to include:
a. Why does the condensation of water vapor (water in the gas phase) to liquid droplets cause a storm to intensify?
b. What is the Latent Heat of Condensation?
c. What happens to the density of air if you heat it?
d. Why does expanded air rise?
e. Would heated, expanded air rise faster or slower than cooler air?
f. Why does surrounding surface air rush in to a Low pressure area, with its rising column of air? Does the surrounding air go straight in or spiral in? Why?
g. What happens to the rising, expanding air if it cools to the same temperature as surrounding air?
h. Does this always happen at the tropopause, or can it happen lower?
i. What causes diverging air to move away from a rising air column?
Don't miss the practice problem on the next page.
F. Application: Sea Breeze.
It is four hours after sunrise. The land has warmed rapidly in the sun. The sea cooled all night and is still much cooler than the land. Air just above the land is warm (24oC), much warmer than air over the sea, and is rising.
Point A marks the base of a small cumulus cloud that has formed above the land. As you know, locally warmed air expands, rises, and cools. When the air is cool enough, water vapor condenses to liquid water, forming cloud droplets.
Answer the following:
a. When water condenses from gas to liquid, heat is released from the water to the air. What happens to the air's density once it gets this extra heat?
(Choose one: heated air expands and density decreases/ heated air contracts and density increases)
b. The cloud base is 800 meters up. The temperature at A is 19oC.
What is the dry lapse rate? ___ oC/____meters.
c. What is the relative humidity at A? _____ %.
d. What is the dew point? ____ oC.
e. Point B is 1000 meters up, 200 meters higher than point A. The temperature is 18 oC.
What is the wet lapse rate? ___ oC/____meters.
f. The air in the rising column of air over the land is
(choose one: more dense/ less dense) than nearby air over the sea.
g. The pressure is higher at (choose one: D / E).