Albedo - Wikipedia
Though temperatures can vary a lot between seasons, they don't change much the air there hardly holds moisture; cold air carries less moisture than warm air. The lower the albedo, the more radiation from the Sun that gets absorbed by the planet, and temperatures will rise. If the albedo is higher, and. To determine the offset of the sonic anemometer temperature, the difference between the mean nighttime (shortwave radiation −2) sonic.
Taking measurements of something with so many variables and influences is clearly going to be a challenge. Satellite data is constrained by the orbit of the satellite. Clouds can be hard to distinguish from white surfaces.
Indirect measurement may also be problematic. The Earthshine project investigated a phenomenon where light reflected by Earth illuminates the dark side of the moon. By measuring the brightness, the amount of albedo - reflectivity - could be estimated. The project reported a counter-intuitive finding. This seems contradictory, as Anthony Watts was quick to note when he voiced his sceptical argument in If higher albedo was having a cooling effect, how could global warming be taking place?
Tricky Business Science constantly seeks to improve itself. The first Earthshine paper Palle claimed to have discovered a very significant cooling effect through a big increase in global albedo.
The results were problematic. Ina new telescope was installed at the Big Bear observatory, where the project was located.
It became evident that the original analysis was in inaccurate. Once corrected, the Earthshine project and the satellite measurements were more consistent. Earth albedo anomalies as measured by earthshine. In black are the albedo anomalies published in Palle In blue are the updated albedo anomalies after improved data analysis, which also include more years of data Palle Over a five-year period, scientists found that albedo did increase slightly.
Research is being conducted into the role of clouds, both as forcings and feedbacks, and the role of albedo in cloud formation. Recent research indicates that global albedo is fairly constant, and having no material effect on global temperatures.
Local effects may be more pronounced. Loss of albedo in the Arctic could heat the water sufficiently to release methane stored in ice crystals called clathrates. Methane is a greenhouse gas far more potent than CO2. Loss of albedo in the Arctic will accelerate warming across adjacent permafrost, releasing methane. Melting permafrost may reduce its albedo, another positive feedback that will accelerate warming.
Ocean warming from reduced Arctic albedo will also accelerate melting at the edges of the Greenland ice cap, speeding up sea level rise. Conclusions Albedo is a subject needing a lot more research. We know the planet is warming, and that human agency is causing it.
Climate Science Glossary
What we cannot say yet is how climate change is affecting albedo, how it might be affected in the future, and what contribution to climate change - positive or negative - it may make.
Illumination[ edit ] Albedo is not directly dependent on illumination because changing the amount of incoming light proportionally changes the amount of reflected light, except in circumstances where a change in illumination induces a change in the Earth's surface at that location e.
That said, albedo and illumination both vary by latitude.
Albedo is highest near the poles and lowest in the subtropics, with a local maximum in the tropics. Tropical and sub-tropical rainforest areas have low albedo, and are much hotter than their temperate forest counterparts, which have lower insolation. Because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes. This has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker being water or ground which is darker color and reflects less heat back into space.
This feedback loop results in a reduced albedo effect.Lesson 5.2.2 - Temperature, Air Pressure, and Humidity
Albedo—temperature feedback[ edit ] When an area's albedo changes due to snowfall, a snow—temperature feedback results. A layer of snowfall increases local albedo, reflecting away sunlight, leading to local cooling.
The albedo effect and global warming
In principle, if no outside temperature change affects this area e. However, because local weather is dynamic due to the change of seasonseventually warm air masses and a more direct angle of sunlight higher insolation cause melting. When the melted area reveals surfaces with lower albedo, such as grass or soil, the effect is reversed: Snow[ edit ] Snow albedo is highly variable, ranging from as high as 0.
If a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack the ice—albedo positive feedback. Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water.
Sea water absorbs more solar radiation than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or in response to increased solar radiation from above, the snow-covered surface is reduced, and more surface of sea water is exposed, so the rate of energy absorption increases.
The extra absorbed energy heats the sea water, which in turn increases the rate at which sea ice melts.
- Letter from Stephanie: Temperature & Albedo
- Albedo Effect
- There was a problem providing the content you requested
As with the preceding example of snowmelt, the process of melting of sea ice is thus another example of a positive feedback.
Because of this, in order to reduce the error of energy estimates, it is important to measure the albedo of snow-covered areas through remote sensing techniques rather than applying a single value for albedo over broad regions. In sunlight, dark clothes absorb more heat and light-coloured clothes reflect it better, thus allowing some control over body temperature by exploiting the albedo effect of the colour of external clothing.
For example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon a-Si: H and crystalline silicon c-Si -based compared to traditional spectral-integrated albedo predictions.