Does size affect albedo?

The grain size has a clear impact on the spectral albedo, where larger grains result in lower albedo, particularly in the near infrared.

How does snow grain size affect the spectral reflectance?

The researchers noted that (1) when the snow grain size becomes larger, the absorption and forward scattering of snow increases, and (2) the snow surface reflectance declines with increasing grain size, and, as the grain size grows, the absorption intensity in near-infrared bands is larger than in the visible bands.

What affects albedo?

For a given area, albedo is determined by more than just the composition of soil, it’s impacted by soil moisture, type of vegetation, and levels of urbanization. Different surfaces on the Earth have different albedos (shown in Figure 1) and that albedo varies with time.

What happens if albedo decreases?

The lower the albedo, the more radiation from the Sun that gets absorbed by the planet, and temperatures will rise.

What is snow grain size?

Snow grain size is a fundamental property of snow and is directly proportional to its surface area. Fresh dry snow tends to have a small grain size (under 0.5 mm in diameter), but as it melts the grain size grows and the larger grains reflect less sunlight.

What increases and decreases albedo?

When you have a snow covered area, it reflects a lot of radiation. This is why you can get terrible sunburns when you’re skiing. But then when the snow covered area warms and melts, the albedo goes down. More sunlight is absorbed in the area and the temperatures increase.

Is high or low albedo better?

The higher the albedo. The higher the albedo, the more the surface reflects light. Snow and ice have high albedos; a dark rock would have a lower albedo.

Is the earth’s albedo decreasing?

Over the past century, there has been a net warming, which has caused Earth’s average temperature to increase by about 0.8°C. An increase in global temperature causes snow and ice to melt, which decreases the extent to which they cover the surface, which then decreases Earth’s albedo.

How do you measure snow grain?

The optical diameter of snow grains can be quantified using near infrared and shortwave infrared reflectance (Kokhanovsky and Zege, 2004; Domine et al., 2006; Matzl and Schneebeli, 2006; Langlois et al., 2010; Montpetit et al., 2012) and now, measurement devices are available commercially and used by several groups.

How big can Sleet get?

sleet, globular, generally transparent ice pellets that have diameters of 5 mm (0.2 inch) or less and that form as a result of the freezing of raindrops or the freezing of mostly melted snowflakes. Larger particles are called hailstones (see hail).

Does snow have a high or low albedo?

The sea ice absorbs less solar energy and keeps the surface cooler. Snow has an even higher albedo than sea ice, and so thick sea ice covered with snow reflects as much as 90 percent of the incoming solar radiation.

How does albedo decrease?

The Earth’s albedo shifts as it warms, resulting in global warming, which causes the melting of ice. This melting of ice causes a decrease in Earth’s white surface area, leading to less solar energy to be reflected (lower albedo) than absorbed.

How does snowpack albedo change with temperature?

Snow albedo typically decreases in old snow-packs, particularly when temperatures are above 0°C and meltwater is introduced into the snow. Albedo values of a mature, wet snowpack are closer to 0.6 and can fall well below this (figure 2.4). Figure 2.4. Measured surface albedo evolution through the melt season at Haig Glacier in the Canadian Rockies.

How does ponding affect the albedo of ice?

On a macroscale, ponded surface water causes significant albedo reductions on snow and ice surfaces, accelerating spring and summer melt on lake ice, sea ice, and glaciers. Ice typically has a lower albedo than snow, but estimates in the literature again vary substantially, from 0.1 to 0.6.

What is the albedo of debris on a glacier?

On glacier surfaces, albedo generally decreases at lower elevations in the ablation zone due to higher melt rates and longer exposure times for the surface. These influences contribute to higher debris concentrations within a given melt season and cumulatively, over many years. The albedo of debris-rich ice is 0.1-0.2.

What is the effective optical radius of spherical snow particles?

The effective optical radius of spherical snow particles is ca. 50 mm for fresh snow, increasing to 100 mm within days and 1 mm or more in mature, melting snowpacks.