clouds

Feb

2024

Solar cells produce rain – weather models show the effects

Solar parks with gigantic dimensions are particularly worthwhile in dry, inhospitable areas with many hours of sunshine. A study using weather models shows that the dark areas can ultimately produce rain in arid areas:

Air inevitably rises above such a large and warming area. This creates convection currents, which are responsible for cloud formation. Only one more ingredient is missing: moisture in the air. And this is exactly what is found in the Persian Gulf, together with winds that bring movement into play in higher layers of air. As a result, conditions regularly come together that provide 0.4 inches (10 millimeters) of rain over an area around three times the size of the underlying solar surface. In Maine, this would correspond to a very rainy day. In the United Arab Emirates, this is the rainfall of the entire summer.

https://www.notebookcheck.net/Solar-cells-produce-rain-weather-models-show-the-effects.801941.0.html

Dec

2023

A revelation about trees is messing with climate calculations

Trees make clouds by releasing small quantities of vapors called “sesquiterpenes.” Scientists are learning more—and it’s making climate models hazy.

Half of Earth’s cloud cover forms around stuff like sand, salt, soot, smoke, and dust. The other half nucleates around vapors released by living things or machines, like the sulfur dioxide that arises from burning fossil fuels.

Trees emit natural volatiles like isoprene and monoterpenes, which can spark cloud-forming chemical reactions.

The team shows that sesquiterpenes are more effective than expected for seeding clouds. A mere 1-to-50 ratio of sesquiterpene to other volatiles doubled cloud formation.

https://www.wired.com/story/a-revelation-about-trees-is-messing-with-climate-calculations/

Aug

2022

Healthy coral reefs produce clouds and precipitation

Fascinating: “Coral reefs produce a volatile substance called dimethylsulphide or DMS which oxidizes in the atmosphere to produce cloud condensation nuclei (CCN). These are tiny sulphur aerosol particles around which water vapor condenses to form clouds, and lead to precipitation. Yet Jones has discovered that even a slight rise in ocean temperatures could affect this natural process, making climate change a significant threat to clouds (and precipitation) seeded by coral reefs. What this suggests is that fewer CCN (cloud condensation nuclei) are produced over coral reefs during high sea surface temperatures and so cloud cover could be expected to be lower or non-existent during high seas surface temperatures. This is a feedback system where the warmer temperatures decrease cloud cover through shutting down the coral’s production of DMS, which in turn further warms the ocean since more sunlight reaches the sea surface. Once the sea surface temperatures exceed the coral’s tolerance level, the corals suffer bleaching, which leads to wide-spread coral stress and even mortality.

Aug

2022

What Are Climate Models Missing?

Not sure if this article is still correct after 10 years of further model refining. I presume that yes, as these water interactions are really difficult to model.

There is now ample evidence that an inadequate representation of clouds and moist convection, or more generally the coupling between atmospheric water and circulation, is the main limitation in current representations of the climate system.

Rather than reducing biases stemming from an inadequate representation of basic processes, additional complexity has multiplied the ways in which these biases introduce uncertainties in climate simulations.

This diversity of responses arises because, at low latitudes, the coupling between water and circulation is disproportionately dependent on the representation of unresolved processes, such as moist convection and cloud formation. The mid-latitudes show more robust responses because much of the energy transport is carried by baroclinic eddies; these, too, are fundamentally coupled to water, but they are much better described and resolved by modern GCMs

Aug

2022

How land management affects the soil and the sky

Interesting article on experiences on the ground (and in the sky), when changing from open to covered soils:

New evidence and research regarding the impact of soil microbes on the creation of precipitation can be accurately characterized as a game changer in our understanding of what it takes to produce rain across the globe. The immediate question is: What can we do to create favorable situations for this ice-nucleation cycle to occur? The answer resides in managing more acres regeneratively. The evidence presented from Chihuahuan ranchers is both strong and compelling. What they are observing and documenting, is not happenstance or mere correlation. It has occurred far too often and too consistently for that to be the case.

It’s increasingly clear that when it comes to rainmaking (and rain retention) we reap what we sow—in the soil and in the sky.

Jun

2022

Forests buffer against variations in precipitation

More forest, more stable rains:

We found a significant buffering effect of forests in the precipitation variability of 10 out of 14 biomes globally. On average, if 50% of precipitation originates from forest, then we find a reduction in the coefficient of variation of monthly precipitation of 60%. We also observed that a high fraction of precipitation from non-forest land sources tends to have the opposite effect, that is, no buffering effect. The average variation of monthly precipitation was 69% higher in areas where 50% of precipitation originates from non-forest land sources in the precipitationshed. Our results emphasize the importance of land cover composition in the precipitationshed to buffer precipitation variability downwind, in particular forest cover.

Jun

2022

Revealing the widespread potential of forests to increase low level cloud cover

Forests and their impacts on low level clouds:

However, changing the forest cover can further affect the climate system through biophysical effects. One such effect that is seldom studied is how afforestation can alter the cloud regime, which can potentially have repercussions on the hydrological cycle, the surface radiation budget and on planetary albedo itself. Here we provide a global scale assessment of this effect derived from satellite remote sensing observations. We show that for 67% of sampled areas across the world, afforestation would increase low level cloud cover, which should have a cooling effect on the planet. We further reveal a dependency of this effect on forest type, notably in Europe where needleleaf forests generate more clouds than broadleaf forests.

Jun

2022

Cloud cooling effects of afforestation and reforestation at midlatitudes

Interesting analysis:

Here, we carefully analyze the situation for reforestation and afforestation (R&A) at midlatitudes, where the warming effects due to vegetation albedo are regarded to be almost balanced by the cooling effects from an increased carbon storage. Using both satellite data and atmospheric boundary-layer models, we show that by including cloudalbedo effects due to land–atmosphere interactions, the R&A cooling at midlatitudes becomes prevalent. This points to a much greater potential of R&A for wet temperate regions than previously considered.

Apr

2022

Revealing the widespread potential of forests to increase low level cloud cover

Forests, afforestation, evapotranspiration, and its cooling effect:

However, changing the forest cover can further affect the climate system through biophysical effects. One such effect that is seldom studied is how afforestation can alter the cloud regime, which can potentially have repercussions on the hydrological cycle, the surface radiation budget and on planetary albedo itself. Here we provide a global scale assessment of this effect derived from satellite remote sensing observations. We show that for 67% of sampled areas across the world, afforestation would increase low level cloud cover, which should have a cooling effect on the planet. We further reveal a dependency of this effect on forest type, notably in Europe where needleleaf forests generate more clouds than broadleaf forests.

The scientists emphasize that land-based climate mitigation through afforestation, forest restoration and avoided deforestation should not be reasoned purely in terms of carbon capture. Instead, policies should include the wider climate benefits that forests offer, including increasing cloud cover for localized cooling and generating rainfall, giving forests additional hydrological value.