Setting Up the Model
To begin investigating the cause of seasons, you'll need to set up a controlled environment that simulates the sun and Earth. Start by placing a heat lamp
horizontally on a stable surface, ensuring it's parallel to the floor. Position a globe relatively close to this lamp, adjusting the distance so the globe receives gentle, even warmth without overheating. This setup represents the sun's rays striking our planet. It's crucial to ensure the lamp is positioned to simulate specific seasonal alignments, such as summer in the southern hemisphere, where the lamp's light should strike the Tropic of Capricorn directly overhead. For consistency, select a region on the globe that absorbs light well, like the South Pacific Ocean, to be near the lamp. Allow the globe to stabilize its temperature for approximately five minutes before taking any measurements, giving you time to observe how quickly the surface heats up and reaches a steady state.
Data Collection Points
With your model established, the next step involves systematically collecting temperature data across various key latitudes on the globe. Using an infrared thermometer, you will measure surface temperatures at specific points: the South Pole, the Tropic of Capricorn, the Equator, the Tropic of Cancer, and the North Pole. Note the approximate angle of the simulated sun relative to each location, which will be crucial for later analysis. For example, the Tropic of Capricorn receives direct overhead light (90 degrees), while the North Pole might receive no light (0 degrees) during a southern hemisphere summer. It's essential to maintain a consistent distance and angle when holding the thermometer, typically about 2 centimeters from the globe, and record these details in your lab notebook. Aim to take at least three readings at each latitude along a single longitudinal line to ensure accuracy and calculate an average for each point. Remember that areas receiving no light should register a uniform temperature.
Analyzing Temperature Data
Once you have gathered all your temperature readings, the process of data analysis begins. The first crucial step is to normalize your data by subtracting the temperature recorded at the North Pole from all other temperature measurements. This adjustment effectively isolates the temperature change directly attributable to the heat lamp, removing any baseline ambient temperature. Following this, you will create a graph where the angle of the simulated sun (in degrees) is plotted on the x-axis, and the calculated temperature change is shown on the y-axis. This graph should be clearly labeled to indicate the simulated season, such as 'Southern Hemisphere Summer/Northern Hemisphere Winter.' Repeating this entire procedure for other seasonal configurations—simulating spring and fall in both hemispheres—will allow for a comprehensive understanding of how axial tilt consistently influences temperature distribution across different latitudes throughout the year.
Exploring Variations and Further Insights
To deepen your understanding and refine your observations, several variations of this experiment can be explored. Substituting the globe with a uniformly colored sphere and drawing latitude lines at 15-degree intervals can help eliminate potential errors caused by variations in color or surface features on a standard globe. Employing a protractor to precisely measure the angle of incident light from the lamp to different points on the sphere will increase accuracy. Expanding the data collection to include additional significant latitudes, such as the Arctic and Antarctic Circles, can provide a more detailed picture. Furthermore, calculating the relative solar energy per unit area for each point and correlating it with temperature can reveal how energy distribution impacts local climate. Comparing the effects of changing the distance between the lamp and the sphere to the effect of axial tilt can also illustrate which factor plays a more significant role in temperature variations. Finally, using a dark-colored cardboard at various angles can offer a more precise measurement of the relationship between light angle, temperature, and energy density.
