No, the wall cloud is a lowered section of the cloud base from which a tornado or funnel cloud descends. The dark cloud at the base of a tornado is called the debris cloud.
Visible signs of a possible tornado often start as rotation in the clouds of a severe thunderstorm, often with a lowered section of the cloud base called a wall cloud. As this happens a cloud of dust may appear near the ground as something called a rear-flank downdraft wraps around the rotation. Then a cone, funnel or elephant trunk shaped projection may lower itself from the cloud base. A cloud of dust and debris under this funnel cloud usually means that the tornado has touched down.
There are two components that make a tornado visible. The first is the condensation funnel or funnel cloud, which forms from moisture condensing inside the tornado. The other component is the debris cloud. This consists of dust and debris lifted into the air by the tornado's winds.
Signs to look for: a lowering of the cloud base rotation in the clouds a hole in the clouds at the back of a thunderstorm Swirling dust beneath the lowered clouds
When warm, moist air rises rapidly into a storm system, it can create a rotating column of air within a dark cloud. The rotation intensifies as strong winds at different altitudes cause the column to stretch vertically, forming a tornado.
The dark gray cloud that blankets the sky and often generates precipitation is called a nimbostratus cloud. These are also clouds that extend far both vertically and horizontally.
Tornadoes occur during severe thunderstorms, typically supercells. So you will typically see thick, often very dark storm clouds. The clouds may take on unusual colors, such as green, yellow, or turquoise. The cloud base itself may appear ragged, and there will usually be a rotating lowering of the cloud base called a wall cloud. The tornado will descend from the wall cloud. See the links for examples of wall clouds.
Sometimes, but not always. In a typical situation you will see a low-hanging cloud beneath a thunderstorm called a wall cloud. As the circulation of the tornado develops, a smaller rotating cloud called a funnel cloud will develop in the wall cloud and extend toward the ground. If the funnel cloud reaches the ground or if there is a whirl of dust beneath the funnel cloud, then the tornado has touched down. This is the classic depiction, however, it does not always happen this way. In many cases, the area where the tornado is forming is obscured by rain. If the air beneath a thunderstorm is dry, the the tornado may develop without a visible funnel. Finally, many tornadoes occur at night, when it is too dark to see them.
A wall cloud is a large, lowering cloud formation that extends beneath the base of a thunderstorm. It often has a wall-like appearance and can be rotating. Wall clouds are typically dark and turbulent, and can sometimes be a precursor to tornado formation.
The funnel cloud of a tornado is full of water droplets just like an ordinary cloud. As a result it blocks light and may appear dark. A tornado may also appear dark if it is lifting large amounts of dark soil into the air. However, not all tornadoes are dark in color. Front-lit tornadoes may appear light gray or even white. Depending on the soil some tornadoes may be light tan, to reddish brown, to gray in color.
Visible signs of a possible tornado often start as rotation in the clouds of a severe thunderstorm, often with a lowered section of the cloud base called a wall cloud. As this happens a cloud of dust may appear near the ground as something called a rear-flank downdraft wraps around the rotation. Then a cone, funnel or elephant trunk shaped projection may lower itself from the cloud base. A cloud of dust and debris under this funnel cloud usually means that the tornado has touched down.
It varies, but it will always occur during a thunderstorm. If that area of the storm is not obscured by rain or the dark of night you will usually see a rotating block of clouds lowered from the main cloud base called a wall cloud. Near this a downdraft will blast a hole in the clouds. Not long afterwards there will likely be strong winds. Then the funnel begins to lower from the wall cloud and a swirl of dust or debris may appear on the ground below it as the tornado connects to the ground.
It is often dark during a tornado not because of the tornado itself, but becasue of the parent thunderstorm. The thunderstorm consists of a very tall cumulonimbus cloud, which blocks out most sunlight.
cirrus
There are two components that make a tornado visible. The first is the condensation funnel or funnel cloud, which forms from moisture condensing inside the tornado. The other component is the debris cloud. This consists of dust and debris lifted into the air by the tornado's winds.
The cloud may appear dark due to the rotation and instability associated with the tornado, but the darkness is more likely from the debris and dirt that the tornado has picked up. The amount of darkness and visibility can vary depending on the time of day, weather conditions, and location.
Tornado clouds typically appear dark and ominous, often taking on a greenish hue due to the light scattering through the storm. As a tornado forms, the cloud may exhibit a rotating, funnel-shaped appearance as it descends from the parent thunderstorm. The distinctive shape and dynamic movement of these clouds serve as visual indicators of severe weather conditions.
These sagging pouches are likely a type of cloud known as mammatus. Such clouds are not necessarily associated with tornadoes, but are a feature of thunderstorms. They are generally more common during severe storms.