In ancient times, clouds were regarded as gods' vehicle of choice. Zeus, the supreme god of Greek mythology, ranked them as the most reliable mode of transportation. And as the one in charge of them, he would know. In the Bible, Jesus is also promised to return to the Earth on clouds, a master plan confirmed in numerous religious illustrations. Today, we use planes for air travel. But a poetic image of clouds as white boats sailing the sky continues to excite our imagination. Still, poetry aside, what are the clouds? And what would it be like to step on one of them?
Clouds are nothing more than lakes of moisture suspended in the air. The heat from the Sun makes the Earth's surface water evaporate. The vapour rises and, meeting the cooler upper atmosphere, condenses into tiny water droplets. These formations of water droplets are clouds. The droplets clump together, grow in size, and fall as rain.
This process is known as the water cycle. And it is similar to what happens in the bathroom when you shower. Warm water evaporates. The vapour rises and fills the room like a cloud. When meeting with the cooler mirror, the vapour condenses on its surface into tiny water droplets. The droplets clump together, grow in size, and run down the mirror.
If you want a full-scale experience inside a cloud, walk into fog. Fog is a cloud on the ground. It also consists of tiny water droplets suspended in the air, but it's not as thick as clouds formed at higher altitudes. On average, clouds above are ten times as dense as fog. However, in certain conditions, super fog can develop when high humidity meets with high air pollution. The super fog may result from a wildfire near ground saturated with water. It can get so thick that you can't see your stretched arm. This is consistent with the density of the heavy rain-bearing clouds. Walking through this fog isn't much different from your average fog experience, apart from severe loss of visibility. A super fog moving to the neighbouring roads can cause serious traffic incidents with multiple casualties.
Fig 1 Road traffic caught in the super fog.
In cold weather, water droplets in the clouds turn into ice crystals, which fall as snow. Feather-like clouds, called cirrus, always contain ice crystals because they form at high altitudes with freezing temperatures. To experience these clouds, you must walk into ice fog. The ice fog consists of tiny ice crystals suspended in the air. It is a rare natural phenomenon because it requires special conditions, such as humidity close to 100% and temperatures below -20 F (-30 C). This fog occurs mainly in arctic and polar regions and can look beautiful under the sunshine, but breathing in the ice crystals is uncomfortable. The ice fog is responsible for such spectacular atmospheric phenomena as luminous pillars, haloes, and sundogs.
Fig 2 Ice fog in Alaska, noon, -40 F (-40 C). Source: Reddit.
Clouds are denser and heavier than the surrounding air, so they try to descend. They are supported by the counterflow of the rising warmer air, which results in uneven pressure inside the clouds. We experience this as turbulence when flying through the clouds on planes. The thin cirrus clouds are not a problem; the main culprits are the heavier cumulus clouds. The low-pressure pockets inside them can make a plane briefly lose altitude, and your stomach "flip" in response. The "flipped" stomach sensation signifies that you're in free fall. And that's what you'll feel when you jump on a cloud and start falling through it toward the ground.
The "flipped stomach" sensation won't last. In about 12 seconds and 1,500 feet (450m) through your fall, you'll reach a terminal velocity of 120 mph (193 km/h). This speed far exceeds the one at which we walk through the fog, so you'll get soaking wet. But that is nothing compared to what you may experience falling through the rain-bearing cumulonimbus clouds. They are towering monsters capable of reaching up to 14 miles (22 km) in height and so dangerous that pilots avoid them at all costs.
Fig 3 Plane flying through the heavy cloud.
The cumulonimbus clouds can harbour thunderstorms with lightning, hail stones, and even tornadoes in North America. So down through them, you may be tossed by powerful counterflows, beaten by large hail, deafened by thunder, burnt by lightning, and twisted by a tornado. These clouds are not the ones to give you an easy ride. But falling through lighter clouds may even be enjoyable if you're an adventurous skydiver with a parachute and a lot of experience. Watch this fantastic video by Steve Rivello called Falling through the Clouds
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