Clouds

Clouds are made up of water droplets, ice crystals or both. Through evaporation and transpiration, water vapor enters the air around us. As the sun warms Earth’s surface, heat is transferred into the air and water vapor in the atmosphere. The warm air rises away from Earth’s surface and begins to cool. The colder the air gets, the less water vapor it can hold. Once it gets cold enough, a process called supersaturation causes the water vapor to transfer back to a liquid or solid state. This transition from water vapor to water droplets or ice crystals is known as condensation. These droplets or ice crystals form around particles of dust, smoke, sea salt or pollution to form condensation nuclei. This step repeats over and over as condensation nuclei bunch together and become visible. The result of this process is a cloud.

Which of the following best describes the relationship between condensation nuclei and clouds?

• One condensation nucleus expands to form a cloud.

• Many condensation nuclei cause clouds to disappear.

• Many condensation nuclei bunch together to form a cloud.

• One condensation nucleus heats air as it rises toward clouds.

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NGSS.MS-ESS2-4

The water droplets that form clouds are so tiny that they remain suspended in the atmosphere. As these droplets bump into each other, they can combine to form larger droplets. When these droplets get too heavy to stay airborne, they fall back to Earth as rain. Ice crystals behave the same way, but produce snow or sleet. The water falling back to Earth is called precipitation. Precipitation returns the evaporated water that formed the cloud back to Earth’s soil and bodies of water. This critical step in the water cycle would not happen without clouds.

Which of the following best describes why precipitation falls to Earth?

• Water droplets or ice crystals heat up and become too warm to remain airborne.

• Water droplets or ice crystals combine and become too heavy to remain airborne.

• Water droplets or ice crystals are pushed out of clouds by wind in the atmosphere.

• Water droplets or ice crystals move around a cloud until they build up enough energy to escape.

Tags

NGSS.MS-ESS2-4

There are 10 different types of clouds. Clouds are categorized by their height in the atmosphere and their shape. There are high, middle and low clouds that fall into three shape categories: cirrus, stratus and cumulus. The terms cirrus, stratus and cumulus refer to both a category of clouds and a type of cloud. Other clouds get their name from a combination of shape category and words like nimbus and alto. Nimbus clouds are clouds that precipitate. Alto clouds are middle height clouds. Take cumulonimbus for example. This cloud name is a combination of cumulus and nimbus. From its name alone, we know it falls under the cumulus shape category and produces precipitation. Similarly, an altostratus cloud is a middle cloud that falls under the stratus shape category. Shape categories are also combined to name clouds, like stratocumulus, cirrostratus and cirrocumulus clouds.

Which of the following clouds most likely produces precipitation?

• cirrus

• cirrostratus

• altocumulus

• nimbostratus

Multiple types of clouds may appear in the sky at the same time in different sizes, shapes and shades of white and gray. Cirrus clouds are wispy, white clouds found high in the sky. Stratus clouds form in layers and look stacked. Cumulus clouds are puffy and have a flat base. Clouds that fall under the nimbus category appear dark and gray. Temperature decreases as height in the atmosphere increases. Because of this, high clouds are made of ice crystals and low clouds are made of water droplets. Middle clouds can be made of either or both. Clouds made of water have more clearly defined edges and outlines than those made of ice.

What are cirrus clouds most likely made of?

• rain

• ice crystals

• water droplets

• both water droplets and ice crystals

When it comes to weather, clouds play a major role. As the sun heats the Earth’s surface, warm air rises. This leaves behind an area of low pressure. This area is filled in by cooler, denser air in the form of wind. Air masses of different temperatures do not mix well when they meet. These collisions create and influence clouds around them. Depending on the difference in temperature, the result may be a rain shower or something as wild as a hurricane. Meteorologists rely on their understanding of clouds and the conditions that create them to better predict the weather. In addition to weather, clouds play a role in regulating Earth’s climate. Clouds reflect incoming radiation from the sun and absorb outgoing heat from the Earth. Since clouds reflect more than they absorb, they have a cooling effect on the planet. Without clouds, scientists say the Earth would be warmer and climate change might be worse.

Which of the following best describes the relationship between clouds and Earth’s climate?

• Clouds regulate Earth’s climate, keeping the planet cooler overall.

• According to meteorologists, clouds predict climate based on wind.

• According to scientists, clouds make climate change happen faster.

• Clouds are created by colliding air masses, resulting in rainy climates.

Tags

NGSS.MS-ESS2-4

NGSS.MS-ESS2-5

NGSS.MS-ESS2-6

True or False: Water is the key ingredient in cloud formation.

• True

• False

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NGSS.MS-ESS2-4

When water evaporates, it becomes

• ice crystals.

• water vapor.

• dust or smoke.

• water droplets.

Tags

NGSS.MS-ESS2-4

NGSS.MS-PS1-4

What happens to warm air as it rises?

• It gets cooler.

• It gets warmer.

• It gets cooler at first, then heats up.

• It remains at its original temperature.

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NGSS.MS-PS1-4

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Which of the following best describes supersaturation?

• Water droplets begin to fall back to Earth from clouds.

• Water vapor transfers back to water droplets or ice crystals.

• Small particles form and bump into each other to form clouds.

• The sun turns water into water vapor as it heats Earth’s surface.

Tags

NGSS.MS-ESS2-4

True or False: Clouds form when one condensation nucleus expands outward.

• True

• False