Geography 1900 Extreme Weather and Climate

Note: The directions that follow are for use with Microsoft Excel 2007/2010 (Windows). A slightly different process is necessary for different versions of Excel (including those for Mac). Refer to the help topics or ask your instructor if you have questions.

1.  Type the X-axis (horizontal) variable name in cell A1 (top left cell). Type the Y-axis (vertical) variable name(s) in B1, C1, etc. This is your first row in the chart, and will automatically create a legend for the chart.

2.  Type X-axis (horizontal/independent) data in column A beginning in Cell A2 (directly below the variable name). Each value goes in a separate cell. You should have a list of values.

3.  Type Y-axis (vertical/dependent) data in columns thereafter (Column B, Column C, etc.) beginning with the second row in the column. Each value goes in a separate cell.

4.  Highlight all of the data you want to plot: select the top-left cell (A1), hold down the Shift key, and

select the lower-right cell. You can also select the first cell and drag your cursor over the other cells.

5.  Select the “Insert” menu at the top of the screen. Click “Scatter” and then “Scatter with Smooth Lines and Markers” (hold your cursor over the option for several seconds to see the names).

6.  Right click in a blank part of the chart and choose Move Chart. Select New Sheet and click OK.

7. Under Chart Tools – Design, click “Quick Layout” . “Layout 1” (upper left option) works well.

8.  To change the chart title, click on “title” at the top of the chart. Type a new title, and hit enter (it won’t change in the chart until you hit enter).

9.  To change the axes labels, click on “Axis Title” on either axis. Type a new label, and hit enter (it won’t change in the chart until you hit enter). Then change the other label in the same manner.

To create other graph types (bar, pie, etc.), select a different option in Step 5. With the exception of Lab 12, your graphs should be scatterplots.

Working with the Kestrel

1.  There are 3 menu options for displaying data on the Kestrel: (1) current data (current reading in large font), (2) min/max/average, and (3) time record (horizontal line across lower screen, and “- for

data” below it).

2.  The variable name is at the top left of every data screen (“BARO” = pressure), and the unit in the top right (“mb” = millibars).

3. Right and left arrows switch menu formats. Up and down arrows switch variables.

4.  The red button in the lower left turns the Kestrel on and off.

5.  The horizontal bar between the arrows selects an option. ( - ). It also exits from menu #3 (stored data).

6.  The camera button in the upper left takes a snapshot.

7.  To access snapshots or autostored data:

•    Goto menu screen #3 (time record) and hit the horizontal bar ( - ) button.

•    Use the right arrow to go forward in time and the left arrow to go back in time.

•    Use the up and down arrows to change between variables at a given time.

This class will discuss weather at various locations with a focus on the United States. We will use maps regularly. Therefore it is important for you to be familiar with U.S. physical geography. The maps on the next two pages illustrate key features (bodies of water, states, mountains, and cities) that you may need to know for exams.

The map below shows states (standard 2-letter code) and bodies of water. Hawaii (HI) is 2500 miles west-southwest of southern California.

This map shows key cities and mountain ranges you will be expected to know. Cities are

indicated by stars and mountain ranges are in gray text.

Laboratory 1: Instrumentation and Measurements (60 pt)

Upon completion of this lab, students will be able to:

•  Identify instruments used to determine weather conditions.

•  Describe types of measurements and their associated units.

•  Explain precision and accuracy.

•  Recognize types of error.

•  Plot data by hand and with Excel

Pre-Laboratory

Meteorologists and climatologists rely on many types of devices to help them determine current weather, forecast future weather, and research past environments. Throughout this course, you will use some of those instruments to gain a greater understanding of atmospheric science. In addition to taking readings, you will have the opportunity to analyze and question your data.

Questioning is one of the most important aspects of science; it helps to reduce error and it leads to new discoveries.

Instruments

The following are instruments that you must become familiar with for future use in this course and possibly beyond!

→ Omega® Infrared (IR) Thermometer

An IR thermometer is a great way to take a temperature reading without being in contact with the object in question. When using an IR thermometer, remember that only the object in question should be in the field of view of the laser. An error will occur in your data if the field of view contains other   objects with differing temperatures. The IR thermometer that you will be using has a range of –60 to 500 °C (–76 to 932 °F). It is accurate within about 2 °C (4 °F).

**CAUTION: Never point an IR thermometer at someone’s eyes!

→  Silva® Explorer Precision Compass

While a compass is a valuable tool to find your way, it can be used for other purposes as well. In upcoming lab experiments, you will use a compass to determine wind direction. (Note: A weathervane is another device that measures wind direction.) Once you see which way the wind is blowing, you can use a compass to figure the specific direction of the wind.

**Keep in mind that meteorologists describe wind direction as which way the wind is coming from.

Measurements

Now that you have become aware of the devices you will use in the laboratory, let’stake a closer look at the types of measurements you will take. The focus of this section is on units of measure.

In the United States, most people use units of measure such as degrees Fahrenheit, inches, and miles per hour. These units are called U.S. customary units. One goal of this course is for you to gain a better understanding of SI (Système International) units,which are the standard units in science. The following table lists the most important units and abbreviations that you will use in this course. Bolded units will be used most frequently. You will be expected to use the correct abbreviations for each unit in your assignments.

The next section will discuss some of the individual variables, including typical values and differences between the systems of measurement.

→ Temperature, Wet-Bulb Temperature, Dew Point Temperature

Temperature can be identified by using three different temperature scales: Fahrenheit, Celsius, and Kelvin.

Look at the differences among the scales. Take note of the boiling point of water, the freezing point of water, and absolute zero on each scale. The SI unit of temperature is Kelvin. However, your labs will focus mainly on the use of degrees Celsius.

Here are some conversion factors to keep in mind, in case you need to convert among temperature scales.

25% relative humidity means that the air is not saturated. When air is saturated (100%

relative humidity) it cannot hold any additional moisture. If more water vapor exists beyond the saturation point, it will condense into clouds. Because the example resulted in only 25% relative humidity, the air is not saturated enough for clouds to form.

→ Pressure

Pressure can be expressed in many different units. Meteorologists tend to use a form of the SI unit of pressure. The SI unit of pressure is the pascal (Pa). Meteorologists often speak in terms of hectopascals (hPa), also called millibars (mb). At Earth’s surface, atmospheric  pressure is around 1000 mb. Most commercial airplanes fly within the jet stream region of the upper troposphere. The pressure at this level is approximately 300 mb. Pressure decreases as you move upward in the atmosphere.

→ Altitude

Altitude is given in terms of feet or meters. The height of the troposphere varies, but a good   estimate is around 11,000 m or 11 km. This is equivalent to about 36,000 ft. In your labs, the focus will be on meters.

→ Wind Speed

You are probably most familiar with wind speeds denoted in miles per hour (mph or mi/hr). A Category 1 hurricane is classified as having wind speeds between 74 and 95 mph. If you   have ever driven a car on a highway, your car’s speed relates similarly to those winds.

Scientists generally speak of wind speeds in knots (kt) or in the SI unit of meters per second (m/s). Category 1 hurricanes have wind speeds of 64–82 kt or 33–42 m/s. While the magnitude of mph and kt are similar, the magnitude of m/s is about half. Use this quick math when trying to get a sense of wind speeds in various units. (**Note: Do not use quick math for actual calculations.)

→ Wind Direction

As noted above, atmospheric scientists refer to wind direction as where the wind is coming from. For example, if wind direction is noted as W or westerly, the wind is coming from the west and blowing toward the east. It also could be stated that the wind is blowing from 270° .  It is important to be able to associate a named direction with a degree angle. The diagram and table below should help you make this connection.

Error, Accuracy, and Precision

The final matter to discuss relates to error. Error is inevitable in scientific study; therefore, you must always be aware of possible sources of error. Knowledge of potential sources of error may help prevent or limit it and will help others when interpreting your results. The types of error you might encounter are instrumental and human error. It is always possible that a device could read variables incorrectly. Human error is very common and can result from using an apparatus incorrectly or from mistakes in calculations. Double check your work and question your answers. Think about the magnitude and sign an answer should have and compare that to the answer you    get through measurement and calculation. If you measure temperature on a brisk winter day, your temperature should be about 35 °F or around 2 °C.

In addition to an awareness of potential sources of error, one should become familiar with accuracy and precision. Accuracy is how close a measurement is to an actual or expected value. Precision is how close a measurement is to other measurements. The example below illustrates  the difference between these terms, assuming the goal is to hit the bull’s eye. To be precise and   accurate, all hits on the target are very close to one another and very close to the bull’s eye.

Graphing

Graphs help meteorologists to interpret weather data to make forecasts. Graphing will be an important part of this lab. There are several necessary features on a graph:

• Title: describes the data being plotted.

• Scale: indicates the x- andy-coordinate values of the data. They do NOT need to start at zero. The range needs to be appropriate (e.g., data from 20.3 – 24.9°C could be

plotted on a scale of 20-25°C).

• Axes labels: indicates the variable being plotted and the units used.

• Legend: if multiple sets of data are plotted, it distinguishes the lines or symbols.

• Data: the measurements or observations plotted. Data points should be placed

accurately relative to the axes scales, and individual points should be distinguishable.

The independent variable is the variable that is being controlled, and is plotted on the x-axis. The dependent variable is the variable that is changing when the independent variable

changes, and is plotted on they axis. Instructions will usually be given to ‘plot [dependent

variable] with [independent variable] ’. For example, when temperatures are collected over

several minutes, the independent variable is time and the dependent variable is temperature.

An example of a complete graph is shown on the next page. Note the location and appearance of all the features mentioned above.