Hidden Weather Factor

As we know, predicting the weather is difficult because of it's great complexity. I believe that it is not that weather is so complicated, it is that the earth on which the weather is created is so messy.

The processes of weather itself are fairly simple. Water evaporates into vapor and when it reaches a certain height where the air is cooler and slighly thinner it condenses on dust particles because the air there cannot hold as much water vapor as the air at the surface where the water evaporated.

This forms clouds, which remain aloft because the droplets of water composing them are so tiny. But when the cloud becomes laden with more water than it can hold, the water falls as precipitation. This often happens where cold air is in contact with warm air because cold air can hold less water vapor than it could when it was warmer.

At the same time we have wind, which moves the weather and transfers heat. The earth heats unevenly. In those areas where it heats more, air rises. In those areas where it heats less, air descends.

This causes movement of air along the surface of the earth and an opposite movement of air high above the earth. People who live near a large body of water know that the breeze tends to move from the sea to the land during the day and to reverse at night. This is because the water is much slower to change temperature than the land so that during the day the sea is cooler than the land while at night the opposite is true.

Unfortunately, weather is not this simple. The earth's surface is very unenven and messy. Masses of land are of many varied sizes as are the stretches of water between them. Mountain ranges block the flow of moisture-laden air so that deserts form.

The spinning of the earth is an important factor in weather because it diverts the path of wind and ocean currents, which are also a factor. Cold ocean currents also create deserts on adjacent land masses because cold water does not produce much evaporation. Warm ocean currents make land at high latitudes much warmer than it would be otherwise, such as the Gulf Stream warming northern Europe. Ocean currents are complex in themselves because they are blocked and diverted not only by the spinning of the earth, the Coriolis Force, but by intervening land masses.

So the reason that weather is so complicated and difficult to predict is not the basic weather processes in themselves but rather that these simple processes operate on an uneven, messy and haphazard earth.

I have noticed another factor which must be an influence in global weather patterns but which I have never heard or seen referred to anywhere. We know that as the earth orbits the sun, the northern hemisphere points toward the sun in June and away in January while the southern hemisphere does the opposite. So overall the earth has the same exposure to the sun throughout the year.

However, we know that the basic cause of weather is the uneven heating of the earth by the sun. What I notice is that there is a lot more land in the northern hemisphere and a lot more water in the southern hemisphere. The northern hemisphere is just over half water while the southern hemisphere is about 90% water.

Land and water absorb solar energy in very different ways. Water has a great capacity to absorb heat, much more so than land. What this means is that the earth does not absorb heat evenly throughout the year. It absorbs more in January and less in June, although it may not feel like it to those who live in northern temperate climates.

This factor is increased by the fact that the earth is actually closer to the sun in January. The earth's average distance from the sun is about 93 million miles but in January it is at about 91 million miles while it is at about 95 million miles in June.

This variation in the absorption of solar energy over the course of a year has got to be an underlying factor in global weather that we are not considering.

There is yet another factor that I have thought of, although it is certainly a minor one. Given that the moon has an albedo of 7%, that is, it reflects that much of the solar energy that falls on it, I calculate that the earth receives 1.24 ten millionths ( 1.000000124 ) more solar energy when there is a full moon than when there is a new moon.