To do: Print out pdf document for Lab H Exercise - Lapse Rates / Stability and Precipitation Patterns

Materials needed: Your atlas, pencil, calculator

Part II. Lapse Rates and Stability

To do: Complete all parts.

Using the DALR and SALR noted on page H-2, answer the questions in the exercises.

Part A. Starting at the bottom and working up, fill in the ovals with the temperature for the parcel at each height. Since the air is unsaturated (as stated in the problem), think about which lapse rate to use. Also, think...what happens to temperature as the parcel rises?

Part B. All questions in this section are linked back to Part A.

Part D. Be specific in your examples. For each lifting mechanism, pick a city or small region where the lifting process is the MAJOR reason for air being forced to rise. Some locations have more than one process active, but I want the dominant lifting process for the location you select. Since south Florida has already been used in the example of convection, please select another location when answering the question for the U.S. Use the atlas if it helps to pick some cities or regions.

Part E. "The Mountain Problem". The air is starting at the surface (sea level here) and will rise up and over the mountain. Question: As the parcel rises, does the air cool or warm? Your answer to this question will determine how the temperature changes. Use the lapse rates provided in the problem and watch your elevations carefully. Example: the DALR is 5.5°F / 1000'. If the air is being lifted over a distance of 3000', the temperature of the air will change by 16.5°F over that height change.

Here is an example (using metric units) so you can see how this is done...and read the discussion below the picture.

So we begin the problem at the lowest elevation on the windward side. Note the temperature and dew point at this location. The first question you ask yourself is: "Is the air saturated?" Question: How do we tell if the air is saturated given the information provided in the problem? If the air is not saturated then we use the DALR, if it is saturated (at the ground) then use the SALR. So, is the air saturated at the ground? No. Therefore we will use the DALR and cool the air by 10°C for each 1000 m the parcel goes up. We watch to see when the temperature cools to the dew point and that occurs right away at 1000m. From this point on upwards, the air is saturated and the parcel cools at the SALR of 6°C/1000m (given in the problem). Finally the parcel temperatures ends up at -2°C at the top of the mountain.

As the air starts down the other side of the mountain, we will change back to the DALR and use it all the way to the bottom of the mountain or to the final height for the question. So warming at 10°C/1000m, the parcel reaches its final temperature of 28°C at the ground on the leeward side. Notice how much warmer it is. These warm (and dry) conditions are what we discussed in a previous lecture as the Chinook wind and the lack of precipitation on this side is called the rain shadow.

NOTE: Use a calculator for these calculations and be careful. If you make a mistake anywhere in the problem, the error will carry through until the end.
NOTE: When doing the problem in the lab exercise, remember that you will be using lapse rates in °F not °C so be careful.

After filling in the temperatures, answer the questions in part F.

Part III: Precipitation Patterns

To do: Complete all parts.

World Precipitation Patterns

Parts A and B: For each of these questions, you are specifically asked to find two different latitudinal regions and explain. Use the precipitation map in your textbook or the atlas to help you find locations that are either very wet or very dry (depending on which question you are doing). Make sure that the two locations that you choose are at very different latitudes or they will count as one. Also make sure that they are not at the same latitude in opposite hemispheres. Choose the location and then describe using the climate controls why the locations are wet or dry.

United States Precipitation Patterns

For these questions use pages 72 and 114 in the atlas to help you. A recurring theme in the early questions is the idea developed with the mountain problem and rain shadow. Keep this in mind when thinking about these questions.

WHEN YOUR LAB IS COMPLETE...Take quiz 8-H_SP.

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