CS 221 – Spring 2017
Lab 3 – Weather Balloon Altitude
Learning Objectives:
- Solving a problem in Excel using an algorithmic solution
- Use of VLOOKUP() and conditional formatting
- Use of a Chart to display data in Excel
General Description:
Weather balloons are released into the atmosphere to gather data from high altitudes. Filled with
Helium, the balloons rise, with a decreasing acceleration, until the balloon reaches a certain altitude
which depends partially on air temperature. As the air cools and warms with the setting and rising of the
sun, the balloon’s altitude will decrease and increase over a 24-hour period. The altitude and velocity of
weather balloons may be modelled with the following formulas:
A(t) = -0.12t4 + 12t3 - 380t2 + 4100t + 220
(in meters)
3
2
V(t) = -0.48t + 36t - 760t + 4100
(in meters per hour)
where t is time in hours since release (note the formulas assume the balloon rises to 220m with
velocity 4100m/hr immediately upon release)
Assuming the balloon is released at midnight, make an hourly report of a balloon’s altitude (in meters)
and velocity (in meters per second) over a 48-hour period. Find the maximum altitude and what time of
day (hour) the balloon reached the maximum altitude. Include a graph of the balloon’s altitude over the
48-hour time period.
Specifications:
The summary is at the top of the report. Put your name, section, the report title, and the overall results
on the first four rows of the report as shown on the example below. Write a formula to find the
maximum value of the numbers in the Altitude column below. Use a VLOOKUP() to find the Time of Day
where the maximum altitude appears in the Altitude column. (Note: it may be helpful to write these
formulas after the details of the table are complete.)
Create a table with columns for hours (since release), altitude (meters), velocity (meters/second), Max
Altitude, and Time (of day).
For the first row of data, set the start Hours to 0 and the Time to 12:00 AM. Use the formulas to
calculate the altitude and velocity. In the max column, write a formula that displays “***” if the altitude
on the row is the highest altitude in the whole table, or nothing otherwise.
For the second row, write formulas to calculate Hours and Time based on the previous row. You should
be able to copy the formulas for the other three columns. You should then be able to copy the second
row to the remaining 46 rows to create the data for the table.
Finally, create a Scatter Chart using the values of the Hours and Altitude columns. Label the chart
“Balloon Altitude by Hour” and label the axes Altitude (m) and Hours since release as shown in the
example.
Example:
Formatting:
- All altitude and velocity values should be displayed with 2 digits passed the decimal point.
- All time values should be in HH:MM AM/PM format as shown above.
- All hours values should be displayed as whole numbers and in bold font.
- Merge cells and apply bold fonts and background colors as shown above on the first five rows.
- For the Altitude values, apply Conditional Formatting / color scales to the values.
- For all values in the Max Alt column (NOT JUST the one that is determined to be the max
altitude!): apply Conditional Formatting / Highlight Cells that are equal to “***”. Specify dark
red font with a yellow background.
- Place the chart between the G to K columns and rows 5 to 21. Use the normal Border Lines tool
to make a thick border around G5:K21 (note: you may have to adjust/shrink the table slightly for
the borders to display).