ATOC 1050 – Summer 2011
Homework 2
Due: June 14, 2011
Make sure your answers are legible, grammatically correct, and have units associated with them if applicable. Each question can be answered in a few sentences. Total possible points: 80.
- You are standing at the surface in Boulder (850 mb) on a hot summer day, where the temperature is 32°C and the dew point temperature is 15°C. An air parcel at your location begins to lift vertically throughout the atmosphere. Assuming its processes are adiabatic, answer the following questions (20 points).
a) What is the lapse rate of your air parcel as it leaves the surface? How do you know (5 points)?
b)You launch a rawinsonde at your location, and measure the environmental lapse rate to be 9°C/km. At 700 mb, what is the temperature of your air parcel? What is the temperature of the environment at that level? Will your air parcel continue to rise, sink back to its original position, or stay at 700 mb? How do you know? Hint – first, you need to figure out the height in kilometers that the air parcel traveled between 850 and 700 mb (15 points).
2.Use the surface map below to answer the following questions (35 points).
a)Estimate the lowest and highest sea level pressure on the map. Be sure to include units (2 points).
b)Determine the direction of the pressure gradient force at: i) Boise, Idaho; ii) Sacramento, California; iii) Phoenix, Arizona; iv) Laramie, Wyoming; v) Omaha, Nebraska; vi) Little Rock, Arkansas; vii) Chicago, Illinois; and viii) Atlanta, Georgia. Indicate the direction and magnitude of the pressure gradient force on the map with arrows that are size appropriate depending on the magnitude of the force (16 points).
c)Identify the city experiencing the strongest wind speeds. How do you know (5 points)?
d)Compute the pressure gradient from i) the Washington/Idaho/Oregon border to the Colorado/Wyoming/Utah border; ii) western to eastern Oklahoma; and iii) western Indiana to eastern Ohio. You will need to estimate the distances between these locations from the scale on the map. Report values in mb/km. Explain what the positive and negative values indicate (12 points).
3. Below is a map of height values on a constant 500 mb pressure surface. Assume that the flow represented on this map is in geostrophic balance. Use this map to answer the following questions (15 points).
a)Draw an arrow showing the speed and direction of the geostrophic wind at each of the four points indicated on the map. The “tail” of each arrow should be at the point and the length of the arrow should be proportional to wind speed (5 points).
b)Draw a second arrow at each point that represents the pressure gradient force (PGF). Again, the tail of the arrow should be at each point, the arrow should point in the direction the force acts, and the length of the arrow should represent the relative strength of the PGF. Label the arrow “PGF” (5 points).
c)Do the same as in (2), but for the Coriolis Force. Label the arrow “CF” (5 points).
4. Using the designators specified below, answer the following questions by filling in the blanks below (10 points).
PGF = Pressure Gradient Force
CF = Coriolis Force
FR = Frictional Force
GR = Gravitational Force
a)The ______is zero at the equator and increases with latitude.
b)The ______acts to accelerate air horizontally from rest.
c)The ______can change the direction air moves, but not its speed.
d)The ______is strongest near the earth’s surface and decreases in importance at higher altitudes.
e)The strength of the ______is visualized on a surface map by isobars.
f)In the Northern Hemisphere, the ______always acts opposite the direction of air motion, but the______always acts to the right of the air motion.
g)For weather applications, the magnitude of the ______acting on any air parcel can be consideredconstant throughout the troposphere.
h)The ______acts to reduce the speed of air.
i)The ______is an apparent force associated with the rotation of the Earth.
j)The ______is always directed toward lower values of pressure.