Our Unpredictable Weather

By “Awake!” correspondent in the Philippines

HAVE you ever been at a picnic or a beach party, when suddenly it seemed as though the heavens opened, and your whole afternoon was washed out in torrential rain? Most of us have, and we may have said some unkind things about the weather at the time. Such inconveniences are small, however, compared with other problems that bad weather can cause. Doubtless, to the relatives of the hundred persons killed each year by lightning in the United States, or to the survivors of typhoons, which have brought death to thousands, the weather can seem to be an enemy.

In reality, though, the weather is a good friend of mankind. By “weather,” we refer to the condition of the atmosphere, particularly that part of it closest to the earth in which we live.

Our atmosphere is like a huge blanket weighing five million billion tons and wrapped around the earth. It protects us from the harsh conditions of outer space, as well as from potentially fatal radiation from the sun. It regulates the heat of our planetary home and carries water from the vast reservoirs of the seas to the land areas, thus making human life possible. Hence, we can be grateful for our weather, even if it causes inconvenience or danger at times.

An Orderly System

Although the weather seems unpredictable, actually it functions in an orderly fashion. Meteorologist Frederick G. Shuman commented recently: “A first casual survey of the atmosphere would likely impress an untutored observer with the randomness of weather events . . . Careful and direct observation, however, reveals order on all scales.”

Most of us are probably “untutored observers.” But a brief survey of how the weather works​—as far as it is understood—​will show that it is truly orderly. In fact, it is another evidence that the earth is well designed for human life and comfort.

A Gift of the Sun

The sun is an amazing source of energy, radiating one million calories per minute for every square centimeter of its huge surface area. Fortunately, only one two-billionth of this vast output reaches the earth, and of this, about a third is reflected right back into space and not used at all by this planet. The remaining two thirds, however, is the ultimate cause of all our weather. Hence, our weather is a gift of the sun. This is true in many ways.

Sometimes children ask why it is that the higher you go, the colder it is, whereas in theory it should get warmer because you are getting closer to the sun. The answer, of course, is that the atmosphere is warmed very little by the direct rays of the sun. Most of the sun’s radiation passes through the atmosphere and warms up the earth’s surface. Hence, the heating of the atmosphere is mostly done from below. This fact has far-reaching consequences.

Over 70 percent of the earth’s surface is covered by water. Much of the sun’s heat goes to warm this up and turn it into water vapor. Some of this vapor, when it rises to higher altitudes, is changed back by the cold into water droplets which form clouds. It takes a lot of heat to turn water into vapor, and when that vapor is condensed into clouds, all that heat is released. This may cause an imbalance in those cold, higher altitudes. Perhaps some turbulence will be caused. But this is all in the cause of getting water to where it is needed, on the land.

Clouds, of course, affect the weather greatly. Not only do they carry rain or snow, but they block out the sunshine, causing cool weather during the day. At night, though, they prevent the earth’s warmth from being lost to outer space. Hence, a cloudy winter night is usually warmer than a clear, starry night.

Great Wind Systems

In olden days, when ships were powered by sails, mariners relied a lot on the weather. They learned that at certain latitudes great winds blew constantly and reliably and would move them long distances over the world’s oceans. These winds are shown on the diagram. However, there were other areas where they had problems. Around the equator, for example, were the doldrums, where they could be becalmed for weeks waiting for a favorable wind. About 2,000 miles (3,200 km) away from the equator was a region that they called the “horse latitudes.” According to one source, this was so named because sailors were at times becalmed there for so long that they started to throw the horses overboard to conserve water!

Undoubtedly, sailors moving with the great winds often blessed the weather, while those becalmed in the uncertain regions said unfriendly things about it. Really, though, both regions are vital to our weather system, and both are caused by the sun.

Our atmosphere is really a gigantic convection system, powered by the heating of the air near the ground in the tropics. This hot air rises to the cooler upper altitudes, and is replaced by air from the North and the South. The great winds you see on the diagram are the result of a complicated circulation system induced by this basic drive, and modified by the rotation of the earth. Those winds are a blessing, in that they blow the rain-bearing clouds from above the seas to the land areas.

But look at the region where the trade winds converge. Yes, it is near the equator, in the doldrums. When all those millions of tons of air rush together in the same latitude, they can only go upward. As they rise from the warmth of sea level to the cool high altitudes, they have to give up some of their load of water vapor. The result is an area of uncertain winds, clouds and rain.

When a body of air ascends, the rotation of the earth makes it revolve like an upside-down whirlpool. Hence, all along this region, bodies of air are being established, in some cases thousands of kilometers across, which are circulating upward, causing low pressure at sea level, clouds and sometimes strong winds. They are called cyclones, and play an important part in moving rain-bearing clouds over the land. Hence, even if the old-time sailors would complain, we can be grateful for this weather system. Similar low-pressure areas are formed where the polar easterlies meet with the prevailing westerlies, where two bodies of air of different temperatures react, or even over locally heated areas.

Two thousand miles (3,200 km) north of the equator exactly the opposite occurs. Here, great bodies of air are moving away from each other​—the trade winds and the prevailing westerlies. The result is that air comes spiraling down from above. The pressure of this air increases, it warms up and an area of fine, cloudless weather is created. This is an anticyclone. The well-known good weather of Hawaii and the Azores comes from stable high-pressure areas that usually hold sway near there. Anticyclones can also form in the polar regions. Coming from there, they will also bring fine, clear weather, but they will be c-o-l-d!

These huge bodies of air, because they are revolving, tend to stay distinct from the surrounding atmosphere. They can move from their place of origin and influence the weather in other locations. Other circulating systems sometimes appear too. A cyclone over the tropical seas may intensify into a typhoon (“hurricane” in the West). This may be hundreds of kilometers across with center winds moving at high speeds. Smaller circulating systems are thunderstorms. Still smaller are the tornadoes, which rip through the central United States each year.

No one fully understands typhoons, thunderstorms or tornadoes. They seem to be systems for relieving unbalance, or perhaps syphoning off excess heat from sea level. But despite their frightening aspect, they undoubtedly play an important role in our atmosphere.

These wind systems are responsible for much of our weather. As high-pressure areas meet up with low-pressure areas, and as both are influenced by the prevailing winds, by the parts of the earth’s surface that they pass over, and by other things, they bring a lot of the variability that we experience in our day-to-day weather.

Man and the Weather

In recent years man has been trying to take the unpredictableness out of the weather. The weather follows laws, but these laws are complicated. Early in this century, British meteorologist Lewis Fry Richardson tried to use mathematical formulas based on the laws of heat and motion to predict the weather. His equations were so long, however, that usually the weather arrived before he finished his calculations. Scientists today use computers. With satellites, balloons, rockets, and so forth, they watch the atmosphere closely, feed information about it into computers, and thus try to foretell the weather. Their short-term forecasts are often quite successful, but the mechanisms for long-term weather patterns still elude them.

Man has also tried to change the weather by seeding clouds to produce rain, dissipating fog at airports, trying to moderate typhoons, reducing lightning strikes and suppressing hail. So far results have been indifferent, and perhaps that is just as well. Can you imagine the lawsuits resulting from flooding caused by man-induced rainstorms?

More problematical is man’s unintentional changing of the weather. For many years, carbon dioxide from his industries seems to have been heating up the atmosphere, while his fluorocarbons and nitric oxides may be destroying the ozone layer, which protects us from dangerous ultraviolet radiation. What the long-term results of this will be no one can say.

Man-induced, too, is the smog that suffocates many cities. Worrisome is the acid rain​—caused by man’s pollutants—​which kills fishes and destroys buildings. Even the prolonged drought that brought devastating famine to North Africa in 1972 happened, according to one source, because of a “long process of climatic change, ecological rape and political mismanagement.”

The Weather as a Friend

In spite of man’s abuse, however, the weather is still his good friend. It is a marvelous system for moderating the temperature and watering the land. Remember, the rain that ruined your picnic was essential for growing food and providing drinking water. And the cyclone that brought it was a part of the great atmospheric convection system.

Even hurricanes and tornadoes undoubtedly play their part, although this is imperfectly understood at present. And really, such events do not have to cost lives. The book Disaster! (prepared by the editors of the Encyclopædia Britannica) points out: “Much of the loss of life from tropical storms and tornadoes can be prevented.” It explains that heeding early warnings and using plain common sense to find protection from the storm could prevent most fatalities. Regarding thunderstorms it says: “The average of more than one hundred persons killed in the United States each year, however, is down from an average of more than four hundred a year in the early decades of this century. Recent research indicates that the loss of life can be even further reduced.” Undoubtedly, if man from the beginning had obeyed his Creator and continued to listen to his counsel, he would have experienced no fatalities at all due to such things.​—Gen. 1:28.

Yes, the weather is a friend of mankind. Let us be grateful that, in spite of what humans have done to the earth, it works so well, and that because of our atmosphere, life is so comfortable on our planetary home.

[Diagrams on page 27]

(For fully formatted text, see publication)

POLAR EASTERLIES

SUBPOLAR LOWS

PREVAILING WESTERLIES

HORSE LATITUDES

TRADE WINDS

DOLDRUMS

TRADE WINDS

HORSE LATITUDES

PREVAILING WESTERLIES

60°

30°

0°

30°

[Diagram]

COLD AIR

LOW PRESSURE

WARM AIR

RISING WARM AIR

COLD AIR

WARM AIR