5: Earth's Energy Budget
- Page ID
- 50827
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Have you ever wondered why the warmest time of day is in the mid-afternoon instead of at noon when the sun is highest in the sky? Or why are evenings warm, even though the sun is almost setting? Both of those questions deal with the concept of Earth's energy budget, namely the balance between incoming solar (shortwave) radiation and outgoing terrestrial (longwave) radiation. The Sun does not heat the Earth evenly. It heats the tropical regions much more than the polar regions. Figure \(\PageIndex{1}\) shows how the Earth's spherical nature changes the angle that sunlight makes with the surface.
In climate science, the concept of Earth's energy budget is crucial because it is the very alteration of that budget, through the introduction of excess greenhouse gases into the atmosphere, that has raised Earth's temperature. In this investigation, we will explore the major components of Earth's energy budget, what affects it, and how excess greenhouse gases have influenced it.
- Explore and quantify the key components of Earth's energy budget.
- Describe how the imbalance in Earth's energy budget, both daily and seasonally, affects temperature.
- Identify ways that humans have impacted the energy budget.
Investigation 4 has 25 questions in total, and the list is continuous, carrying over from the first to the last subpages of the investigation.
- 5.1: Energy Balance
- This page explains Earth's energy budget, likening it to a financial budget where absorption of solar radiation leads to temperature changes. It notes that about 70% of solar energy is absorbed, with temperature increases occurring when incoming radiation surpasses outgoing. It highlights temperature lag after noon and details seasonal variations, emphasizing that the warmest days follow the summer solstice due to energy balance principles.
- 5.2: Global Energy Balance
- Regions near the Equator receive more incoming solar radiation than they lose, resulting in warmer temperatures, while areas poleward of 38°N/S experience the opposite trend. Natural processes redistribute heat and affect weather patterns, and climate change may disrupt these energy dynamics in unpredictable ways.
- 5.3: Energy Budget and Climate Change
- This page explains Earth's energy budget, detailing how energy surplus causes warming and energy deficit leads to cooling, especially concerning climate change. It features an energy budget diagram depicting incoming solar radiation and outgoing radiation, underscores the significance of energy balance and reflectivity, and notes that despite annual fluctuations, the average global temperature has risen consistently since 1880, highlighting the relevance of energy budget analysis.
- 5.4: Other factors affecting Earth’s Energy Budget
- Albedo plays a crucial role in Earth's climate, as it quantifies the reflection of sunlight by surfaces, with lighter colors reflecting more. The melting of high-albedo ice enhances warming by exposing low-albedo surfaces, creating a positive feedback loop. We examine clouds' dual effects; they cool the Earth by reflecting sunlight but can also trap heat, depending on their type.
- 5.5: Accessible Descriptions
- This page provides accessible descriptions for the images in the Investigation
Thumbnail: Sunlight Angle from Equator to Poles, by Robert Simmon is in the Public Domain.