Insolation: Amount of solar radiation reaching an area, measured in watts per square meter.
Objectives
Explain how the sun's energy affects Earth's surface.
Understand insolation's dependence on season and latitude.
Comprehend how Earth's tilt affects daylight, insolation, and seasons.
Develop skills to describe environmental concepts visually.
Factors Influencing Insolation
Latitude:
Latitude: Distance from the equator, measured in degrees.
Equator (0° latitude) receives more sunlight than poles (90° latitude) due to:
Angle of Sun's Rays: Perpendicular at the equator, leading to concentrated solar intensity.
Atmosphere Thickness: More atmosphere at higher latitudes absorbs/reflects more solar energy.
Tilt of Earth:
Earth is tilted at 23.5° on its axis.
This tilt affects the angle of the sun's rays, altering insolation and causing seasonal changes.
Solar Intensity and Latitude
Equator: More direct sunlight, higher solar intensity.
Higher Latitudes: Sunlight is spread over a larger area and passes through more atmosphere, resulting in lower solar intensity.
Earth's Tilt and Seasons
June Solstice: Northern Hemisphere tilted toward the sun (longest day, start of summer in the north).
December Solstice: Northern Hemisphere tilted away from the sun (shortest day, start of winter in the north).
Equinoxes (March & September): Equal tilt, equal daylight, and transition between seasons.
Albedo
Definition: Portion of light reflected by a surface.
High Albedo: More light reflected, less absorbed (e.g., snow, ice).
Low Albedo: More light absorbed, more heat (e.g., water, urban areas).
Urban Heat Island Effect: Urban areas with low albedo surfaces absorb more heat, making them warmer than rural areas.
Practical Example
FRQ Practice: Determine the season in the Northern Hemisphere based on Earth's tilt.
Conclusion
Understanding the concepts of insolation, Earth's tilt, and albedo are crucial in explaining the variations in climate and temperature across different regions and seasons.