Scientific Observations of an African Boy

In the early to mid 1990's, when I was ~12 years old, I used to literally run wild and free in wide open fields in Kenya, East Africa (which lies on the Equator). After long periods of playing I would get tired and I lay down on the grass to catch my breath. In my view, was the sky.

On cloudy days, I noticed that if there is no object in my peripheral view (Trees or buildings), staring at the clouds for a few minutes caused a sense of "vertigo." Somehow, the fast movement of the large clouds that are so far away messed up my spatial perception in relation what I was seeing causing a kind of "dizziness!" I can describe this feeling as a brief confusion about whether it is the clouds moving relative to me, OR I was moving relative to the clouds.

However, with stationary objects in my peripheral view, this effect did not occur. I figured that having something in my view relative to the clouds served as reference that enabled correct spatial orientation. I showed some of my friends this and they reported the same feeling! I eventually grew up and forgot this...until I saw some NASA images a few years ago.

"Along the equator you can see a line of patchy clouds extending all the way across the map. There are small breaks in this line. Over the Indian Ocean the line broadens out to form a rather big patch that covers all of Indonesia and portions of northern Australia"

These large fast-moving clouds along the equator are as a result of a combination of three factors: Firstly, sunlight hits regions at the equator at the most incident angle, thereby causing more evaporation of water which eventually condense to form clouds. So it is expected that there will be more clouds at the equator than anywhere else.

Secondly, is the effect of equatorial convergence commonly known as the Inter Tropical Convegence Zone. In the ITCZ warm air from north and south converges causing the air to rise and form thunderstorms. It is estimated there are 40,000 thunderstorms around the world every day. You can see many of them along the ITCZ.

Lastly, the cloud's fast movement is caused by rotation of the Earth on its axis. At the equator, the Earth's surface moves 40,000 kilometers in 24 hours. That is a speed of about 1040 miles/hr (1670 km/hr or 0.5 km/sec). This is calculated by dividing the circumference of the Earth at the equator (about 24,900 miles or 40,070 km) by the number of hours in a day (24). As you move toward either pole, this speed decreases to almost zero (since the circumference of the spinning circle at the extreme latitudes approaches zero). The friction between the trees, mountains, tall buildings and the air above is agitated by the high velocity. The effect of these obstacles on land add up to swirl the air above them, in turn spinning the clouds faster than anywhere on Earth!

It appers that humans have a problem correctly percieving relative velocity as the comparator in question becomes larger and moves faster. Think of this, how fast is the Earth revolving around the sun?

Let's see, in 1 year the Earth revolves around a circle with a radius of 93 million miles.

(Assuming orbit is free from any eccentricity)

Speed of revolution = (Perimeter) / (Time).

Speed of revolution = (3.14 x 2 x 93,000,000) / (365 x 24 x 60)

Speed of revolution =~ 1,112 miles per Hour.

Sure doesn't feel like it. Also from space, Earth looks like its barely moving. I am just a small spec in this universe. Too small to even correctly percieve speed and size correctly.