Weather Lab

Part I

Purpose:

To become more familiar with different types of temperature scales and how to measure temperature itself. We were also taught about due point and relative humidity in this lab as well.

Background Information:

There are many various ways to measure temperature. One ways is by using a thermometer, which is a tool used to measure a temperature of system. However, there are many times of thermometers that one could use the most commonly used is the Mercury or alcohol thermometers. According to http://galileo.phys.virginia.edu/outreach/8thgradesol/ThermometersFrm.htm the thermometer has some very interesting facts;

"The most common thermometer utilizes a liquid, either mercury or alcohol. A glass bulb, filled with this liquid, is connected to a glass capillary tube. When heated, the liquid expands from the bulb into the capillary tube, so that the change in temperature corresponds with the change in height of the liquid. Mercury is commonly used because there is a wide temperature range at which it is liquid: from -38.9 C to 356.7C.

More recently, alcohol thermometers have supplanted the use of mercury thermometers in schools because of dangers associated with mercury. If you use a mercury thermometer in the experiment, be especially careful that it does not break.

There are other, more complex types of thermometers as well. A Galileo thermometer applies the fact that liquids expand faster with increasing temperature than do solids. It is made of a column of fluid that contains solid spheres with a density close to that of the liquid. If the sphere's density is less than the liquid, it will float; if it is greater than the liquid, it will sink. As the temperature increases, the liquid will expand faster than the solid and the liquid's density will decrease at a quicker rate, so that the spheres will eventually sink. Each sphere in a Galileo thermometer is a specific density so that it will sink at an exact temperature, thus displaying the temperature of its surroundings. The photo at the left is of a Galileo thermometer, which are no longer commonly used.

A third type of thermometer, a bimetallic thermometer, is used in household applications such as the thermostat. This thermometer is made of two strips of different types of metal which are sandwiched together and rolled into a coil. The metals expand at different rates with an increase in temperature, causing the coil to either wind or unwind. A pointer connected to the bimetallic coil indicates the temperature.

Relative humidity is a measure of how much water vapor is in the air compared to the max amount that the air can hold. This helps our bodies either be comfortable in or not because if the humidity is too high then there is too much moisture in the air making our bodies hot. Once it evaporates it cools our skin. Due point is what is measure to determine relative humidity. The definition of due point is the temperature at which water vapor condenses to a liquid.

In 1745, Swedish naturalist Carl von Linne` devised a centigrade scale to measure temperature. He began his scale with the freezing point of water at zero degrees and set the boiling point of water at 100 degrees. Andrew Celsius used the same number of deviations in his scale, but he instead reversed the order to where the boiling point was zero and the freezing point was 100. The International Committee of Paris adopted the measurements of freezing and boiling points of water as fundamental markers for temperature scales. The Celsius scale was reversed, and in 1948 was revised to set the triple point of water at .01 degrees Celsius and boiling point at 99.975 degrees Celsius. The Celsius scale is used primarily in scientific investigation worldwide and in weather reporting for daily atmospheric temperatures everywhere but the United States.

Procedure:

To begin the lab we had to become comfortable with converting Fahrenheit to Celsius. We were giving three temperatures of Fahrenheit; 232Ñ", 0Ñ", and 50Ñ" and had to convert them to the Celsius temperatures; 111 1/9Ñ", -17 7/9Ñ", and 10Ñ". Next using a mercury thermometer our group measured the temperature of our fingers, tap water, and ice water in both Celsius and Fahrenheit degrees.

Fingers = 28.1Ñ"C = 82.58Ñ"F

Tap Water = 19.1Ñ"C = 66.58Ñ"F

Ice Water = .5Ñ"C = 32.9Ñ"F

Our next step in this lab was to measure dew point. In order to do this we had to add water to an aluminum container with ice, while stirring it with a thermometer. Once the dew formed on the outer surface of the container we were able to measure the temperature. After recording the temperature we then removed the dew, the ice and re-measured the temperature. We then had to wait for the dew to completely leave the container and then we measure the temp again to figure an average of the two temperatures.

Dew point depression=dew point-ambient air temperature

Our final step to perform was to find the relative humidity in the lab, 48Ñ".

Data:

Formulas and Equations

100Ñ"C=212Ñ", and 0Ñ"C=32Ñ"F

100Ñ"C-0Ñ"C = 212Ñ"-32Ñ"F

xÑ"C-0Ñ"C yÑ"F-32Ñ"F

Fahrenheit to Celsius Tc=5/9 (TF-32)

Celsius to Fahrenheit TF=9/5 Tc+32

Kelvin=273+C

Conclusion:

This lab could have been improved if I had actually attend class the day the experiment was performed. I had surgery on this day so it was very hard to visualize the lab. However, if I were guessing the only possible way to improve the accuracy of the temperature measurements would be to leave the thermometers in the substance measured long enough to record an accurate temperature. Also using different types of thermometers could have varied the findings.

Part II

Purpose:

To become more acquainted with the relationship between pressure, volume, and temperature of an ideal gas.

Background Information:

Terminology

Pressure-the