Since elementary school, I was always fascinated by the sky and everything else that makes it – the sun, the moon, the stars, and the clouds, which is as far as my limited imagination allowed me to perceive. However, what captivated me the most to date were the clouds. These wonders triggered my creativity and imagination in that they were always changing in shape, color, and movement.
What always intrigued me about them most is that somehow they didn’t seem to fall from the sky, even in those moments when they appeared to be so heavy. Clouds are hardly ever still. Sometimes, we don’t even notice they are even moving at all.
While at other times, we may see them moving very fast across the sky in a particular direction. However, the million-dollar question is, do the clouds move? What speed do they move, what determines that speed, and how does this affect their shape? Read on to find out.
- Vertical versus Horizontal Cloud Movement
Do Clouds Move and at What Speed?
Some people argue that when you see clouds moving, they aren’t. It is supposedly the effect of the Earth’s spinning. Mind-boggling, right? The truth is that, yes, they do move, but not of their own accord. We see clouds, which are, in reality, condensed water vapor being blown away by the wind. The spinning of the Earth does affect the movement of the clouds because the spinning affects how the wind blows, even at high altitudes.
The wind causes the clouds to move in the direction it’s moving, most of the time. At other times, we feel the wind blowing in the eastern direction and notice clouds moving in the opposite direction. How is this possible, we wonder? Wind direction and speed varies with altitude. Clouds can travel for hundreds of miles in a day with the same speed as that of wind. For instance, if a cloud is at an altitude of 6,000 Ft., it will be moving at the wind’s speed at 6,000 Ft. (assuming the cloud is thin and light).
Clouds found near the Earth’s surface are usually thin and lighter due to friction and tend to be moved quite easily by the wind. Still, not all clouds can be moved by the wind. If the clouds are packing lots of moisture, ice crystals, and water droplets to form giant furry-looking opaque puffs, the clouds’ solidity can endure intense speeds.
Meteorologists usually use these clouds to predict weather patterns. However, the speed at which clouds move depends on the altitude at which they are formed. Low clouds can form at approximately 5,000 Ft. High clouds such as cirrus form from 30,000 Ft. and above. High clouds are usually moved by a jet stream (fast-moving air) and can at times move at 100 km/hr. During a thunderstorm, clouds typically move at a speed of between 30-40 km/hr.
Generally, the wind increases in speed with height and undoubtedly near the surface. However, there are occasions where this might not be the case and especially when there’s high atmospheric pressure. In such instances, it’s incredibly astounding to see the speed of wind at 20,000 Ft. being equal or less than the speed of wind at 2,000 Ft. Those are the moments where we feel the wind gently blowing around us, but on looking at the sky above, find the puffs barely moving at all.
Vertical versus Horizontal Cloud Movement
Naturally, clouds move horizontally. If you are a lover of nature like I am and love visiting the wild, you may notice a cloud on one side of the mountain, but after a few moments, see it on the opposite side. It’s the horizontal movement of clouds due to wind.
Clouds can also move vertically. We sometimes see a cloud hanging very low in the sky gradually rise higher in the sky. It’s caused by hot air from below rising upwards through a process known as convection. In such scenarios, clouds tend to move upwards where the air is cooler. The vertical movement of clouds happens when water vapor condenses at different altitudes while being driven by the wind. Essentially, meteorologists use the speed at which clouds move to determine the upcoming weather.
Other Factors that Affect How Clouds Move
Solar radiation causes convection, a process that’s mostly responsible for water and air movement around the Earth. The convection technique works when heat energy from the sun causes warm, humid air masses to be lighter and rise, which results in the denser, colder air getting pushed down till it’s heated and rises.
Temperature Inversion Layers
Temperature inversion layers, also called thermal inversions, occur when the natural atmospheric heat gradient is reversed. Usually, the air adjacent to the ground is relatively warm, and it gets colder as the altitude increases. When a thermal inversion occurs, the colder air gets stuck beneath the warmer air, leaving stagnated air trapped on the Earth’s surface.
I have been a witness to numerous thermal inversions, and I believe that you have too. It could be you were just unaware when it happened. Have you ever risen only to find a blanket of fog laying low in your yard and dew on the grass? A clear example of a thermal inversion. When the wind starts blowing or the atmospheric temperature heats up, the temperature inversion will disperse.
A dynamic lift happens when two air masses of varying temperatures meet. The denser air mass lifts its lighter counterpart higher into the sky.
The wind can blow a warm air mass up and over a mountain, where it will rise and cool as a result.
How Do Clouds Form?
From giant palls rising high up in the sky to thin wisps sneaking between the stars at night, clouds come in shapes and sizes. Their ever-changing characteristics make them brilliant food for thought as they feed our imagination. In addition to igniting creativity, clouds serve some critical roles for sustaining life on Earth, including helping in determining weather patterns and changes, protecting us from the sun’s UV rays, and from extreme cold at night. But how are clouds formed?
Clouds are formed when the cloud condensation nuclei (dirt, sea salt, or dust) combine and attract water vapor. When the nuclei ascend, the vapor condenses and forms ice that eventually becomes cloud droplets. These globules are very light, which makes them accumulate as they float about. Once they mix with air, they become the cottony formations that we usually see suspended in the atmosphere. I used to mostly wonder why clouds don’t fall to the ground, given their density. Clouds come from tiny droplets of water which fall eventually, but very slowly as rain or snow.
What are the Different Categories of Clouds?
Clouds are generally found in the closest layer of the atmosphere to the Earth. As these cottony puffs rise and fall, they appear in fathomless variations. To create order, scientists grouped all clouds in three broad categories:
Usually found at the highest surface and appear at approximately 10,000-60,000 Ft.
These generally appear at about 6,000-25,000 Ft.
These are the clouds closest to the Earth’s surface and usually hover at 6,500 Ft. or below.
The above categories are further sub-divided according to the shape of a cloud.
What are the Various Shapes of Clouds?
The shapes of clouds vary due to several factors. The more water vapor rises to the sky, the older water droplets are pushed upwards, which forms a cloudy with an inflated top. The flat stripe shows the point where the troposphere starts to get too cold for vapor for clouds with a flat base. The shape of clouds can also be affected by wind. Since it’s possible for the wind to move clouds, it can merge two clouds, separate two clouds, or make some clouds look thin and light. Clouds, according to shape, are categorized as follows:
Usually classified as:
- Cirrus clouds are made of ice crystals and look thin, wispy, and are usually white.
- Cirrostratus clouds appear white but are very clear and tend to cover the whole sky, which exudes a glow-effect on the sun and moon.
- Cirrocumulus clouds also appear as white sheets across the sky. They also appear undulated.
Typically appear grayish and are categorized as:
- Altocumulus clouds have lots of water but don’t usually produce rain. They mostly appear patchy, rippled, and generally in rows.
- Altostratus clouds also blanket the sky but are way darker than cirrostratus clouds and may make the sun or moon appear unclear. They can also signify a storm.
- Nimbostratus clouds are dense, dark, and produce both rain and snow.
Fall into four divisions:
- Cumulus clouds are whitish and usually appear prominent and cottony. Can assume the shape of a familiar object.
- Cumulonimbus clouds appear thick and dense and are usually a sign of tornadoes, hailstorms, or thunderstorms.
- Stratus clouds look like a thin layer in the atmosphere, gray.
- Stratocumulus clouds are sparse and look like a honeycomb. Appear both whitish and gray.