Our Self: Um blogue desalinhado, desconforme, herético e heterodoxo. Em suma, fora do baralho e (im)pertinente.
Lema: A verdade é como o azeite, precisa de um pouco de vinagre.
Pensamento em curso: «Em Portugal, a liberdade é muito difícil, sobretudo porque não temos liberais. Temos libertinos, demagogos ou ultramontanos de todas as cores, mas pessoas que compreendam a dimensão profunda da liberdade já reparei que há muito poucas.» (António Alçada Baptista, em carta a Marcelo Caetano)
The Second Coming: «The best lack all conviction, while the worst; Are full of passionate intensity» (W. B. Yeats)


A inteligência artificial está ainda longe de ser uma ferramenta confiável e sem defeitos, mas produz melhores resultados do que a ignorância natural (e poupa-nos à presunção e arrogância)

Albedo is a measure of how much light that hits a surface is reflected without being absorbed. It's expressed as a ratio or percentage, with 0 meaning no reflection (all absorption) and 1 meaning total reflection (no absorption).

Albedo is a crucial concept in climatology and environmental science because it affects the Earth's energy balance. Surfaces with high albedo, such as snow and ice, reflect a large portion of incoming solar radiation back into space, which can have a cooling effect on the planet. Conversely, surfaces with low albedo, such as dark asphalt or forests, absorb more solar radiation, contributing to warming.

The albedo of various surfaces is influenced by factors such as color, texture, and composition. Understanding albedo helps scientists predict and model climate patterns, assess the impact of land use changes, and study feedback loops in the Earth's climate system.


The energy reflected by soils with high albedo is essentially bounced back into the atmosphere or into space. When sunlight hits a surface with high albedo, such as light-colored soils, snow, or ice, a significant portion of that solar radiation is reflected rather than absorbed. This reflected energy can have several consequences:

Cooling effect: Surfaces with high albedo reflect a large portion of the incoming solar radiation, which reduces the amount of energy absorbed by the surface itself. As a result, these surfaces tend to remain cooler than surfaces with lower albedo, which absorb more solar radiation and thus heat up more.

Global energy balance: Reflected energy contributes to the overall energy balance of the Earth's atmosphere. When energy is reflected back into space, it does not contribute to warming the planet's surface. This balance of incoming and outgoing energy influences Earth's climate and temperature patterns.

Albedo feedback: Changes in surface albedo, such as melting snow or ice, can contribute to feedback loops that affect climate. For example, as snow and ice melt due to warming temperatures, they expose darker surfaces underneath (such as soil or ocean water), which have lower albedo. This leads to increased absorption of solar radiation and further warming, creating a positive feedback loop that amplifies temperature changes.

Regional climate effects: The reflectivity of surfaces with high albedo can influence local and regional climate patterns. For example, large expanses of snow and ice in polar regions reflect a significant amount of sunlight, contributing to the cooling of those areas. Changes in the extent of these high-albedo surfaces can therefore impact regional climate dynamics.

Overall, the energy reflected by soils with high albedo plays an important role in Earth's energy balance and climate system, influencing temperature patterns, feedback processes, and regional climate effects.


The difference between the albedo values of the tundra and a pine forest lies in how much solar radiation each type of environment reflects.


The tundra is characterized by vast expanses of frozen soil covered by a thin layer of mosses, lichens, and some low-growing plants.

The albedo of the tundra is typically high because the snow and ice cover reflect a significant portion of the incoming solar radiation.

Even during the summer months when snow cover may be minimal, the exposed soil tends to have a light color and lacks dense vegetation, contributing to its high albedo.

Pine forest:

A pine forest has a denser canopy of vegetation, with tall trees and a closed canopy of foliage.

The albedo of a pine forest is generally lower than that of the tundra. This is because the tree canopies and dense foliage absorb more solar radiation, reducing the amount of light that is reflected back into the atmosphere.

Additionally, the forest floor within a pine forest may be darker due to organic matter and decomposing vegetation, further contributing to a lower albedo compared to the tundra.

In summary, while the tundra tends to have a higher albedo due to its snow and ice cover, a pine forest typically has a lower albedo due to the greater absorption of sunlight by the vegetation and darker forest floor.


While the absorption of sunlight by trees contributes to the overall energy balance of a forest, it's important to note that the albedo of the forest canopy and surrounding surfaces still influences how much solar radiation is absorbed versus reflected. Forests with darker canopies and lower albedo will tend to absorb more solar radiation, contributing to warming of the immediate environment.

However, the complex interactions between sunlight absorption, albedo, and other factors within forest ecosystems make it difficult to make a simple yes or no statement about whether tree absorption compensates for a low albedo. Instead, these processes interact in dynamic ways that vary depending on factors such as forest type, season, latitude, and local environmental conditions.


In temperate forests, the sunlight absorbed by forest trees does contribute significantly to the energy balance of the ecosystem. However, whether this absorption is enough to fully compensate for the low albedo of the forest canopy depends on various factors and can vary depending on specific conditions. Here are some considerations:

Seasonal Variation: In temperate regions, the amount of sunlight absorbed by forest trees can vary seasonally due to changes in leaf cover (e.g., deciduous trees losing their leaves in winter) and solar angles. During the growing season when trees have leaves, they absorb a considerable amount of sunlight for photosynthesis. However, in winter or during periods of leafless conditions, the albedo of the forest canopy may have a greater influence on the energy balance.

Canopy Structure and Density: The structure and density of the forest canopy also play a role. A denser canopy with more foliage will absorb more sunlight, contributing to greater energy absorption within the forest. However, denser canopies may also limit the amount of sunlight reaching the forest floor, which can affect understorey vegetation and microclimatic conditions.

Surface Characteristics: The forest floor and understory vegetation also contribute to the overall albedo of the forest ecosystem. Surfaces covered by vegetation, such as shrubs or mosses, may have different albedo values compared to bare soil or snow-covered surfaces. Additionally, factors such as soil moisture and ground cover can influence surface reflectance.

Radiative Forcing: The net effect of sunlight absorption and albedo on the energy balance of a temperate forest depends on radiative forcing, which considers both incoming solar radiation and outgoing longwave radiation. While forest trees absorb sunlight, they also emit longwave radiation as heat. The balance between these processes determines whether the forest ecosystem gains or loses energy.

In summary, while sunlight absorbed by forest trees is an important component of the energy balance in temperate forests, it may not always fully compensate for the low albedo of the forest canopy. The interaction between sunlight absorption, albedo, and other environmental factors is complex and can vary depending on the specific characteristics of the forest ecosystem and prevailing conditions.


Este post com outputs do ChatGPT é um contributo talvez inútil para clarificar algumas confusões conceptuais a propósito deste outro post. Em conclusão, tenho de concordar com o outro contribuinte: «plantar árvores pode ser bom, pode ser mau ou pode ser pouco relevante ou mesmo irrelevante».

1 comentário:

Anónimo disse...

«plantar árvores pode ser bom, pode ser mau ou pode ser pouco relevante ou mesmo irrelevante».

Quando a burrice natural procura a burrice artificial, só se pode concluir que a decadência e o colapso na sociedade actual estão iminentes.