Lab 2 Earth-Sun Geometry Since we can assume that the Sun’s rays strike Earth in straight, parallel paths, we see that the zenith angle of any location is the same as the number of degrees separating your diagrams should show that Sun angle varies with season and location. Since such variability greatly influences weather patterns, it is useful to be able to calculate the noon Sun angle for a given latitude we must first define a few terms (Figure 2-5) the location and the place receiving direct solar rays.
The Correct Answer and Explanation is:
To correctly calculate and understand the noon Sun angle at a specific location on Earth, we must define a few key concepts related to Earth-Sun geometry. These include:
- Zenith Angle: The angle between the Sun and the point directly overhead (zenith).
- Solar Declination: The latitude at which the Sun is directly overhead at solar noon (i.e., where the Sun’s rays are perpendicular to the surface).
- Latitude of the Observer: The location on Earth for which we are calculating the noon Sun angle.
Correct Answer:
The zenith angle of any location is the same as the number of degrees separating the location’s latitude from the latitude receiving the Sun’s direct rays (solar declination).
300-Word Explanation:
The noon Sun angle refers to the angle of the Sun above the horizon at solar noon (when the Sun is highest in the sky for that location). This angle is crucial because it determines the intensity of solar energy a location receives, which in turn affects temperature, weather, and climate.
To calculate the noon Sun angle, we use the formula:
Noon Sun Angle = 90° – |Latitude of Location – Solar Declination|
This formula shows the relationship between the observer’s latitude and the solar declination. The zenith angle is the difference between the Sun being directly overhead (90°) and the actual position of the Sun in the sky. For example, if you’re at 40°N latitude and the solar declination is 23.5°N (which happens during the summer solstice in the Northern Hemisphere), then:
Noon Sun Angle = 90° – |40° – 23.5°|
Noon Sun Angle = 90° – 16.5° = 73.5°
This means the Sun will be 73.5° above the horizon at noon.
As the Earth orbits the Sun, the solar declination changes throughout the year, ranging from 23.5°N at the June solstice to 23.5°S at the December solstice. This causes seasonal variation in the Sun angle at different locations. At the equator, Sun angles remain relatively high year-round, while at higher latitudes, the variation is more extreme.
Understanding how the zenith angle and Sun angle change with latitude and season helps meteorologists, climatologists, and geographers explain and predict Earth’s climatic zones and weather patterns.
