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Aerosols & Clouds

"Take a deep breath. Even if the air looks clear, it's nearly certain that you've just inhaled tens of millions of solid particles and liquid droplets." -NASA Climate

Clouds (masses of water drops or ice crystals suspended in the atmosphere) and aerosols (tiny, airborne solid and liquid particles) play important roles in earth's climate and interact with each other, and the ocean, in complex ways.

Clouds are the key regulator of Earth's average temperature. Some clouds contribute to cooling because they reflect solar energy or shortwave radiation back to space. Other clouds contribute to warming because they trap some of the energy the Earth emits. PACE will provide estimates of cloud properties (cover, height, phase, brightness, and droplet size) that are essential for climate model assessment.

Aerosols can be found in the air over oceans, deserts, mountains, forests, ice, and every ecosystem in between. They drift in Earth's atmosphere from the stratosphere to the surface and range in size from a few nanometers to several tens of micrometers. One of the PACE polarimeters will be focused on characterizing aerosols in the atmosphere.

Learn more in the resources listed below about how PACE will explore clouds and aerosols, as well as use these data to help make better estimates of what is going on in the ocean.

Get out your (virtual) paint brush and color this interactive scene created by Sarah Amiri
Get out your (virtual) paint brush and color this interactive scene created by Sarah Amiri
Learn how PACE's OCI is being designed to revolutionize the study of ocean color
Watch the global distribution of aerosols released by Australian bushfires [more]
Track how aerosols change throughout the year using NASA satellite data [more]
Examine how clouds change the flow of energy from the Sun to the Earth [more]
Follow along in this interactive web tool to learn how aerosols impact our world
Learn how PACE will help clarify connections between aerosols, clouds, and climate [more]
See how cyclones, dust storms, and fires spread aerosols around the globe [more]
Learn how PACE technology will decipher Earth's ocean-aerosol-cloud system [more]
Discover the delicate balance between the ocean, atmosphere, and climate [more]
Step into the shoes of NASA’s Cloudsat mission team [more]
Watch how aerosols can have a big impact on our planet [more]
Step through this online lesson to explore aerosols and their impact on climate [more]
Get up to speed on aerosols with this informative background article [more]
Investigate the climate system in the classroom [more]


This is a very complicated question, and is explained in more detail in reports by the Intergovernmental Panel on Climate Change (IPCC) and others. However, as a basic overview, as light from the sun enters the earth's atmosphere, aerosols scatter the Sun's light, which results in a local cooling effect. However, some aerosols also absorb light, which can result in a local warming effect, depending on the amount of aerosols, their altitude, and the brightness of the underlying (Earth's) surface at the place in question. The net direct effect of this scattering and absorption by aerosols is cooling, when averaged across the globe. This means that aerosols have offset part of the positive forcing (warming) due to greenhouse gases such as carbon dioxide (CO2). However because the lifetimes of aerosols in the atmosphere are very short compared to greenhouse gases, and because aerosols vary a lot over time and from place-to-place, it is not correct to say that aerosols cancel out the effects of greenhouse gases. Additionally, aerosols can have complex influences on cloud formation and evolution, which further modify the Earth's energy balance.

PACE Aerosol & Cloud Scientists (14-Dec-19)
Clouds are formed when water vapor in the atmosphere condenses. Dependent on factors such as the temperature, they may be formed of liquid water droplets, ice crystals, or a mixture of both.

PACE Aerosol & Cloud Scientists (14-Dec-19)
Aerosols are small particles suspended in the atmosphere. Some are natural and some are human-derived. Examples are smoke from fires, dust from deserts, volcanic ash from eruptions, and urban haze from industrial activities. We are interested in them for reasons including climate change, health and air quality, hazard monitoring, ecology, and more.

PACE Aerosol & Cloud Scientists (14-Dec-19)
Monitoring Earth's cloudiness from space is useful for many reasons. Two of the most important are for providing input to weather forecasts and for climate monitoring purposes. Clouds reflect the Sun's visible light and can trap Earth's emitted thermal radiation, so changing the cover and properties of clouds can affect the Earth's energy balance.

PACE Aerosol & Cloud Scientists (14-Dec-19)
Yes and no. The dictionary definition of aerosols applies to both - small particles suspended in a gas. While the contents of some spray cans could contribute to your home's "aerosol conditions" at times, spray cans are not considered to be a big source of the aerosols that we study in the earth's atmosphere.

PACE Aerosol & Cloud Scientists (14-Dec-19)
We typically study aerosols using data collected by instruments mounted on Earth-looking space satellites. These instruments record the amount of sunlight reflected from the Earth's surface and from the atmosphere. As aerosols scatter and absorb the sun's radiation, they affect the brightness and color (wavelengths of light) of these observations. We can use information from multiple colors of wavelengths, and measurements taken from different angles and/or polarization states of light, to determine the characteristics of aerosols and what at is happening on the land/ocean below.

PACE Aerosol & Cloud Scientists (14-Dec-19)