This website is about complex scientific research, and we, therefore, often can’t avoid mentioning certain technical terms. Depending on your background, these may or may not be part of your vocabulary. In fact, the research performed at ATTO is so multidisciplinary that even if you are a scientist working in atmospheric research, you may not be familiar with terms specific to soil science. But we want all of our readers to take the most out of this website. Hence, we’ve created a glossary which explains the more and less well known technical terms mentioned on this website. Whenever they appear on a page or in a news post, a link will send you here. Consequently, this glossary will be expanded over time, as more and more content appears on this website.


Aerosols are solid or liquid particles suspended in a gas, usually air. They span a size range from 0.01 to 100 µm in diameter (1µm equals 1/1000 of a millimeter). Aerosols can be natural or anthropogenic. Natural aerosols include so-called bioaerosols such as pollen or spores, as well as things like dust, smoke from wildfires and droplets of sulfuric acid emitted during volcanic eruptions. Anthropogenic aerosols include sulfate aerosols created by the burning of coal and oil and smoke from human-caused activities such as the burning of tropical forest.

Black and brown carbon

Black carbon (BC) and brown carbon (BrC) are aerosols emitted from combustion of biomass. While black carbon is mainly produced by incomplete combustion at high temperatures, brown carbon is the product of low-temperature combustion or smoldering fire. Human activities are their main source, they include emissions from diesel engines, cook stoves and wood burning. However, natural forest fires for example also release black and brown into the atmosphere. Both are important agents in climate because particles absorb sunlight: black carbon mostly in the visible light, giving it its black color and brown carbon partially in UV light, giving it its brownish-yellowish color. Thereby they generate heat in the atmosphere, which warms the air and can affect regional cloud formation and precipitation patterns. When deposited on light, reflective surfaces such as snow and ice, they change the albedo of that surface, accelerating melting.

Cloud condensation nuclei

Cloud condensation nuclei are aerosols that act as seeds for clouds. For water to condensate from its gaseous into its liquid state, it typically requires a solid surface. Aerosols suspended in the air provide such a surface. Hence they act as a seed, or nuclei, for water condensation to form clouds.

Cloud droplets

Once water condensates around cloud condensation nuclei, it forms a cloud droplet. On average, cloud droplets are 10-15 µm in diameter, but their size varies greatly. Depending on the size of the cloud condensation nuclei and the stage of growth, they reach diameter so of 100 µm (0.1 mm). Cloud droplets are surrounded by water vapor and only make up a millionth of the volume of a cloud. Yet there is an immense total number of cloud droplets in any given cloud. Light is scattered repeatedly as it travels through a cloud, making them appear substantial and opaque.

The Intertropical Convergence Zone

The Intertropical Convergence Zone (ITCZ), more commonly known as the doldrums, is the region near the equator. Intense sun and warm water heat the air raising its humidity and making it buoyant. It is also here, where the trade winds of the Northern and Southern Hemispheres come together. Aided by the convergence of the trade winds, the buoyant air rises. As the air rises it expands and cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. This hot yet humid climate is the reason rainforests, such as the Amazon formed in a belt along the Earth’s equator. The location of the ITCZ, however, shifts over the course of the year due to the tilt of the earth axis. This drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes.

Trade winds

Between about 30 degrees north and south of the equator, the Earth’s rotation causes air to move towards the equator. In the northern hemisphere, it moves in a southwesterly direction, in the southern hemisphere in a northwesterly direction. This is called the Coriolis Effect. The Coriolis Effect, in combination with an area of high pressure, causes the prevailing winds – the so-called trade winds – to move from east to west on both sides of the equator across this 60-degree “belt.” As the wind blows to about five degrees north and south of the equator, both air and ocean currents come to a halt in a band of hot, dry air. This region near the equator is called the Intertropical Convergence Zone.

Uatumã Sustainable Development Reserve

The Uatumã Sustainable Development Reserve (Portuguese: Reserva de Desenvolvimento Sustentável do Uatumã) is a protected area in the state of Amazonas, Brazil. It covers over 4200 km2 along the Uatumã parts in parts of the lower Amazon plateau and the Amazon plain. It is inhabited by a traditional population of about 1300 people in some 20 communities. They seek to preserve nature while maintaining and improving the lives of the population through sustainable agriculture, extraction, and fishing.

Volatile Organic Compounds

Volatile Organic Compounds, short VOCs, are carbon-based organic chemical compounds that evaporate easily. Thus, they exist in gaseous and vaporous form at room temperature. There are both anthropogenic and naturally occurring VOCs. The majority of biological VOCs are produced by plants, but animals and microbes also contribute to the VOC emissions, the most common one being isoprene (C5H8). But there are thousands of different biological VOCs that are very varied and occur practically everywhere. They also serve a broad range of purposes. For example, they are responsible for most scents or odors (such as the typical smells of trees), play an important role in communication between plants, and are used to repel harmful animals or attract pollinators. Furthermore, VOC influence climate through their production of organic aerosols and their involvement in the production of ozone.