Freezing rain

Rain falls from the sky.

It falls through warm air first. This turns snow into rain. Then, the rain falls through cold air near the ground. The rain is still liquid, but it is very cold.

When the rain hits something, it turns to ice.

This ice is called glaze. It covers trees, wires, and cars.

This ice can be very heavy. It can break tree limbs. It can also knock down power lines.

Ice on the roads makes driving hard.

It makes cars slide on the ground. This kind of weather is called an ice storm.

Freezing rain is a special kind of weather. It is made of liquid rain drops.

First, snow falls from the clouds. It hits a layer of warm air. This warm air melts the snow into rain. Then, the rain falls into a thin layer of freezing air near the ground. The rain stays liquid, but it becomes supercooled. This means it is below the freezing point.

When these drops hit a surface, they freeze instantly. This happens through a way called nucleation. The ice forms a smooth coating called glaze.

Glaze ice can be very heavy. It can break tree limbs or knock down power lines. This can cause power outages. Ice on roads is also dangerous for cars. It makes it hard to drive without sliding.

Freezing rain is very bad for planes. The ice can change the shape of the wings. This makes it hard for the plane to fly. Large storms with much ice are called ice storms.

Freezing rain is a unique kind of weather that can change the world around us. Unlike snow or ice pellets, freezing rain is made of liquid droplets.

It happens when rain stays liquid even though it is below the freezing point. This state is called being supercooled. When these drops touch anything, they turn into ice instantly. This creates a smooth coating called glaze ice.

When a lot of this ice builds up, it is called an ice storm.

This weather works through a specific series of steps in the sky. First, snow falls from the clouds and hits a layer of warm air. This warm layer melts the snow into rain. Next, the rain falls into a thin layer of freezing air near the ground. If this cold layer is very shallow, the drops do not have time to freeze into pellets. Instead, they stay liquid as they fall. When they hit a surface, they freeze through a process called nucleation.

Scientists and weather stations use special tools to find this rain. You cannot see freezing rain directly on a standard weather radar. However, experts look for something called a brightband on radar images. This is a bright area that shows where snow is melting into rain.

By looking at the height and slope of this band, they can guess where freezing rain might fall. They also use dual-polarized radar to see the shape of the falling drops. This helps them tell the difference between rain and ice.

Ice storms can cause many problems for people and nature. Heavy glaze ice can weigh down tree limbs until they snap. This often happens to pine trees because their needles catch the ice.

The weight can also pull down power lines and cause outages. In February 1994, a huge ice storm hit the Southern United States. It caused over $1 billion in damage in places like Mississippi and Tennessee. Another major storm hit eastern Canada and New York in 1998.

Freezing rain is also a major danger for airplanes. Ice can build up very quickly on the wings of a plane. This changes the shape of the airfoil, which is the part of the wing that helps the plane fly. This makes it harder for the plane to stay in the air.

In 1994, American Eagle Flight 4184 crashed near Chicago because of ice on the wings. Pilots often have to climb into warmer air to escape the freezing rain. This can be a hard job when ice is already building up. Sometimes, the ice even creates strange things like "ghost apples" in Michigan.

Freezing rain is a specific type of precipitation that occurs when liquid raindrops freeze immediately upon hitting a surface. Unlike sleet, which consists of solid ice pellets, freezing rain is made entirely of liquid droplets. These droplets remain in a liquid state even though they are at temperatures below the freezing point of 0 °C. This state is known as being supercooled. When these supercooled drops strike objects like trees, power lines, or roads, they undergo a process called nucleation. This process causes the liquid to turn into a smooth, transparent coating of ice known as glaze ice.

The formation of freezing rain requires a very specific arrangement of air temperatures in the atmosphere. It often begins with snow falling from higher altitudes. As the snow descends, it enters a layer of warm air located above the ground. This warm layer melts the snowflakes, turning them into liquid rain. As the rain continues to fall, it must pass through a shallow layer of subfreezing air near the Earth's surface. If this cold layer is deep, the rain might freeze into ice pellets before hitting the ground. However, if the layer is very shallow, the drops do not have enough time to freeze mid-air. They remain supercooled until they make contact with a surface below.

This weather pattern is frequently linked to the approach of a warm front. During these events, warm air is advected, or moved, into higher altitudes while cold air remains trapped near the surface. This can lead to a phenomenon called cold-air damming. In this setup, very cold and dry air is held in place by a high-pressure system. The warm air, often coming from the Gulf of Mexico, acts as the fuel for the melting process.

Meteorologists cannot see freezing rain directly on standard weather radar. Instead, they must use indirect methods to identify it. One method involves looking for a "brightband" on radar imagery. A brightband is a highly reflective area that shows where snow is melting into rain. By analyzing the height and the slope of this brightband, experts can estimate where melting is occurring. They can then use numerical prediction models to determine if that melting will result in freezing rain at the surface. Additionally, dual-polarized radar can help by sending both vertical and horizontal waves to deduce the shape of the precipitation.

When freezing rain accumulates in large quantities, it is classified as an ice storm. These storms can be incredibly destructive to infrastructure and nature. Glaze ice can reach a thickness of several centimeters. This weight is often too much for plants to support. Trees, especially pine trees with their ice-catching needles, may snap under the heavy load. This weight can also pull down power lines, causing widespread outages. For example, a massive ice storm in February 1994 caused over $1 billion in damage across the Southern United States. This storm impacted states like Mississippi, Tennessee, Alabama, and North Carolina.

Freezing rain poses an extreme hazard to aviation due to rapid structural icing. When ice builds up on an aircraft, it changes the shape of the airfoil. An airfoil is the curved surface of a wing that generates lift. As the shape changes, lift is reduced and drag is increased. This raises the stalling speed, making it difficult for the plane to maintain altitude. In 1994, American Eagle Flight 4184 crashed near Chicago after ice accumulated on its wings. To avoid this, pilots often try to climb into warmer air. However, because freezing rain is often accompanied by a temperature inversion, climbing can be a dangerous task.

Beyond its dangers, freezing rain can create unusual natural sights. In Michigan in 2019, observers found "ghost apples." These are icy shells left behind when freezing rain coats a rotting apple. Because the apple has a lower freezing point than water, the fruit inside may defrost and slip out while the ice shell remains. Similar shapes have been seen in other places, such as an ice shell left by a vehicle in North Carolina. These strange occurrences highlight how freezing rain can transform the physical world in unexpected ways.