Nimbostratus cloud facts for kids

Quick facts for kids Nimbostratus cloud
Nimbostratus with pannus
Abbreviation	Ns
Symbol
Genus	Nimbostratus (rain, layered)
Altitude	500–5,500 m (2,000–18,000 ft)
Appearance	Dark and featureless layer cloud full of water vapor; responsible for rain and snow
Precipitation	Yes: rain, ice pellets, or snow; sometimes virga

A nimbostratus cloud is a dark, grey cloud that looks pretty much the same all over. These clouds usually bring steady rain, snow, or sleet. But don't worry, they don't cause lightning or thunder!

Even though they often look low in the sky, these clouds actually start forming higher up. Then they grow bigger, spreading out and covering a large area with rain or snow. The name 'nimbostratus' comes from a Latin word, nimbus, which means "cloud" or "halo". These clouds can grow very tall, like some big puffy clouds. But they spread out even wider across the sky.

What Do Nimbostratus Clouds Look Like?

Nimbostratus clouds have a soft, unclear bottom edge. This bottom can be anywhere from close to the ground up to about 3,000 meters (9,800 feet) high. Even though the base is usually dark, it can sometimes look like it's glowing from the inside when you see it from the ground.

These clouds are very thick, usually about 2,000 to 4,000 meters (6,600 to 13,000 feet) from top to bottom. You can find nimbostratus clouds all over the world. However, they are more common in the middle parts of the Earth, like where the United States or Europe are.

How Do Nimbostratus Clouds Form?

Nimbostratus clouds often form along a warm front or an occluded front. Imagine warm, moist air slowly rising over cooler air. As this warm air goes up, it creates nimbostratus clouds. Sometimes, these clouds are joined by thinner stratus clouds that bring less rain. Before these clouds arrive, you might see higher clouds like cirrostratus clouds and altostratus clouds. Often, an altostratus cloud will get thicker and drop lower, turning into a nimbostratus cloud.

Unlike cumulonimbus clouds (which cause thunderstorms), nimbostratus clouds are not usually linked to storms. However, if a warm front is very unstable because the warm air is hot and humid, you might find some cumulonimbus clouds mixed in with the nimbostratus. If lightning happens, it would only be from those embedded cumulonimbus clouds. It can be hard to tell which cloud is causing the rain from the ground. But cumulonimbus clouds usually bring heavier rain with bigger drops. It's rare to see both cumulonimbus and nimbostratus together. Usually, you'll only find nimbostratus at a warm front, and sometimes at a cold front.

What Weather Do Nimbostratus Clouds Predict?

Nimbostratus clouds often look very plain and dark.

Nimbostratus clouds usually mean that a warm front or occluded front is coming. This means you can expect steady, moderate rain or snow. This is different from the shorter, heavier rain that a cold front's cumulonimbus clouds bring. The rain or snow from nimbostratus clouds can last for several days, depending on how fast the weather system moves.

Sometimes, nimbostratus clouds produce virga. This is when rain or snow falls from the cloud but evaporates before it reaches the ground. After a warm or occluded front passes, nimbostratus clouds are usually replaced by stratus clouds or stratocumulus clouds.

Where Did the Name Nimbostratus Come From?

The way we name clouds today started with Luke Howard in 1802. He studied clouds in France and grouped them into three main types based on how they looked: cirriform (wispy), cumuliform (puffy), and stratiform (layered). He also added two names for clouds that were a mix: cumulostratus and nimbus. The term nimbus was used for complex clouds that grew tall enough to produce a lot of rain.

Later, in the 20th century, a group studying clouds changed the definition of "nimbus." They decided it was a type of layered cloud. So, they renamed it nimbostratus. This new name was officially published in 1932 in the International Atlas of Clouds and of States of the Sky. This change meant that only cumulonimbus clouds kept the "nimbo" part in their name to show they were the main rain-producing storm clouds.

Types of Nimbostratus Clouds

Nimbostratus clouds are very thick and look quite plain, so they are not divided into smaller types or varieties.

• Rain or Snow Features: Nimbostratus clouds are known for bringing rain or snow. Sometimes, this precipitation doesn't reach the ground and is called virga. When it does reach the ground, it's called praecipitatio, and it can be quite heavy because the cloud is so deep.
• Accessory Clouds: Sometimes, you might see ragged, low clouds forming below the main nimbostratus cloud deck, especially during rain. These are called nimbostratus pannus.
• How They Form from Other Clouds: Nimbostratus clouds can form from cumulus clouds and cumulonimbus clouds.
• Changing from Other Clouds: Nimbostratus can also form when altocumulus clouds, altostratus clouds, or stratocumulus clouds completely change their shape and become nimbostratus.

How Nimbostratus Clouds Relate to Other Clouds

Nimbostratus clouds are related to other layered clouds because they don't form from strong updrafts like puffy clouds do. However, other layered clouds usually stay at one or two levels in the sky.

• Stratus clouds are low-level clouds, forming from near the ground up to about 2,000 meters (6,600 feet).
• Altostratus clouds are middle-level clouds, forming from about 2,000 meters (6,600 feet) up to 7,600 meters (25,000 feet) depending on where you are in the world.
• Cirrostratus clouds are high-level clouds made of ice crystals. They often create halos around the sun or moon. They form at very high altitudes, from 3,000 meters (9,800 feet) up to 18,000 meters (59,000 feet).

Of the clouds that grow vertically, cumulonimbus clouds and cumulus congestus clouds are most similar to nimbostratus. This is because they also grow very tall and can bring moderate to heavy rain. Other cloud types like cumulus clouds, stratocumulus clouds, altocumulus clouds, and cirrocumulus clouds are less similar to nimbostratus.

See also

• Nimbostratus virga
• Cumulonimbus cloud
• List of cloud types