Tag: Equator

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Rossby Waves and Earth’s Climate

Rossby Waves and Earth's ClimateWe have previously discussed the movement of air around the Earth, and the circulation pattern called the Hadley cells. Another important factor in Earth’s climate is Rossby waves.

Because the equator is hot, heated air rises and moves away from the equator, dropping its moisture as it cools. At about 30 degrees latitude, the now dry air falls back to the Earth, producing deserts. As the air reaches Earth’s surface, it moves north and south, creating the trade winds in the subtropical area and the prevailing mid-latitude winds in latitudes between 30 degrees and the polar regions.

A wide range of things alters this simplified picture. When greenhouse gases like carbon dioxide accumulate, they reflect infrared radiation causing the Earth’s atmosphere to become hotter. This effect isn’t uniform, however. Because of melting sea ice, Earth’s poles are affected by greenhouse gases more than the area of the equator. This causes a thermal imbalance between the poles and the equator affecting circulation around the poles and creating Rossby waves.

As the thermal imbalance has become greater and the air more wobbly in recent years, that affects the jet stream. The wobbles this past year have caused the northern jet stream to go further south than usual, bringing cold into Arizona in late spring. When the jet stream swung north, it brought hot tropical air toward the poles. On its way north, it brought unusual amounts of water into Oklahoma while Anchorage, Alaska, got temperatures over 90 degrees for the first time ever. Rossby waves is the name applied to the meandering high-altitude winds that have a major influence on Earth’s weather.

All of this shows us how fragile Earth’s climate is. Weather patterns depend on a wide range of variables which include the:
*size of the Earth’s atmosphere
*tilt of the Earth
*distribution of land compared to water
*chemical makeup of the atmosphere
*kind of radiation coming from the Sun and how that radiation is absorbed and reflected
*nature of Earth’s surface (whether ice or black dirt)
All of those factors go into making Earth a habitable planet.

We exist on this planet because of the precision design and construction of Earth and its atmosphere. The fact that it has stayed stable long enough for human life to exist for thousands and thousands of years is a testimony to the careful design and construction. Proverbs 8 finds “wisdom” speaking about its role in the creation process. Wisdom says she was there before the creation (verse 22-23) and that wisdom was a part of the preparation of the heavens (verse 26-28).

As we see the results of the small changes that have happened to the atmosphere in the past 100 years and the instability of Rossby waves, we wonder at Earth’s design and the wisdom of God who created it.
— John N. Clayton © 2019

Reference: Astronomy, December, 2019, page 64.

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Why Is The Equinox Important?

Why Is The Equinox Important?

Today, March 20, 2019, is a special day as the spring equinox arrives for the Northern Hemisphere. Today the Sun will set exactly in the west and tomorrow it will rise exactly in the east when observed from the Equator. The day will be exactly 12 hours long and night will be exactly 12 hours long. After today in the Northern Hemisphere, the days will be longer than the nights. Officially spring arrives today at 9:58 PM Greenwich Mean Time (5:58 PM Eastern Daylight Time where we live).

In reality, all of this is an exaggeration of the real situation. Don’t expect a balmy spring day if you live in Michigan (as we do) or other northern areas. Ice and snow have to melt, and the land has to warm up. Nevertheless, the equinox does remind us of Earth’s design and how many variables control our existence on this planet. What does happen on this day is that the Sun will be directly overhead at noon at the equator.

During the northern winter, Earth’s tilt has caused the Sun to be overhead south of the Equator. As the Earth moves around the Sun, the Sun’s location relative our planet will drift north until June. When the summer solstice occurs on June 21, the Sun will be overhead at 23 degrees north latitude. The more direct sunlight not only warms the Northern Hemisphere, but it avoids overheating the Southern Hemisphere.

If Earth did not have a 23-degree axis tilt, the Sun would beat down on the equator from directly overhead all year long. The Equator would become so hot that nothing could live there. The northern and southern latitudes would both freeze. Wind belts created by air rising violently at the equator would be hurricane force 24/7. We see that happening on planets in the solar system that do not have an axis tilt.

Ancient people knew that the position of the Sun changes throughout the year. They used elaborate but primitive observatories to determine the time to plant and harvest based on the Sun’s position. Unfortunately, this led many cultures to worship the Sun. Nowhere does the Bible encourage or condone the worship of any celestial bodies. The Bible recognizes the seasons and the role of the Sun as designed by God for human existence. (See Genesis 1:14-15).

The ancient psalmist David said it (Psalms 8:4) and the writer of Hebrews quoted it (Hebrews 2:6), “What is man that you keep him in mind or the son of man that you look after him?” The equinox is a good time to be reminded of God’s provisions for us and thankfully worship the Creator, not the creation.

–John N. Clayton © 2019

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Autumn Equinox and Season Design

Autumn Equinox and Season Design
We have just passed the autumn equinox and what we call “the first day of fall.” It will be late December before fall officially ends at the winter solstice. On the first day of fall here in Michigan, it was unseasonably hot, and people were griping about “where is the cool fall weather we are supposed to have?” Long before the first day of winter on December 20-21, we will have snow. Is there something wrong with the seasons, or is the trouble with our understanding?

“Equinox” suggests that the length of the day is equal to the length of the night. The Sun is overhead at the equator, and from now until December 20 it will be directly overhead at progressively greater southern latitudes until it reaches just past 23 degrees south latitude. Here in the north, the Sun’s elevation above the horizon will get progressively lower, meaning that less and less of the Sun’s energy will strike the Earth’s surface so the weather will get cooler.

The problem with this simple picture is that there is a lag in the seasons. During the summer months in the Northern Hemisphere the lakes and oceans warm from the sunshine. Water has a high specific heat, so that heat is stored and is released slowly. That means we stay warm longer than expected in the fall. In the Southern Hemisphere the picture is complicated by the fact that the Earth is closer to the Sun during their summertime, so the radiation is more intense. That might be a problem except that the Southern Hemisphere has more water than the Northern Hemisphere because oceans cover more of the southern Earth’s surface. With that greater storage and absorption capacity moderates the temperatures in the Southern Hemisphere.

The autumn equinox reminds us of the incredibly well-designed system of the Earth. It is easy to over-simplify the seasons and the equinoxes and solstices, but the system functions remarkably well. Without that careful design, the weather picture would be far more unstable than it is. Proverbs 8:22-31 speaks of wisdom’s involvement in all of the creation. We are just now beginning to understand how the system works and how our use of Earth’s resources affect the system.
–John N. Clayton © 2017