Weather Patterns

Meteorology is the study of the physics and chemistry of the atmosphere.

Weather refers to the atmospheric conditions that result from the interaction of temperature, moisture, winds, and clouds.

All weather is due to four things:

1.         Sun

            a.         The sun is just a star like all the others we see in the sky. It appears so much bigger because it is so much closer.

            b.         The sun is a big ball of burning hydrogen which uses 3.6 million tons of hydrogen fuel per second.

            c.         At this rate, the sun has enough hydrogen to burn for about 30 billion years.

            d.         Energy is released when two hydrogen atoms join to make one helium atom in a nuclear reaction. The energy of the reaction is released and reaches our planet.

            e.         70% of the solar energy is absorbed by the atmosphere and the planet and 30% is reflected back.

2.         Atmosphere

            a.         The energy that is absorbed by the atmosphere is changed to heat which warms the planet.

            b.         As warm air rises it cools and the water vapor condenses.

            c.         As water vapor condenses on particles of dust in the air clouds are formed.

            d.         When clouds get too big and heavy, the moisture returns to Earth as precipitation.

            e.         Clouds also reflect and absorb some energy.

            f.         Without clouds it would be much warmer because less energy would be absorbed.

            g.         In the desert it gets very hot because the air is dry so more energy hits the Earth. Also, at night it is very cold because there is no moisture in the air to hold the heat in.

3.         Shape and Movement of the Earth

            a.         Because the Earth is spherical, more energy is absorbed at the equator than at other areas.

            b.         At the equator, air is warmed and rises. This air travels north and south toward the poles.

            c.         Cool air from the north and south poles replaces the rising warm air.

            d.         This tends to distribute the heat from the equator toward the poles.

            e.         As Earth rotates the winds curve. This is called the Coriolis effect.

            f.         Because the Earth is tilted on its axis, parts of the Earth are pointed toward or away from the sun at certain times of the year. This causes the seasons.

                        i.         In autumn and winter, the northern hemisphere is tilted away from the sun so days are shorter and temperature is cooler.

                        ii.        In spring and summer, the northern hemisphere is tilted toward the sun so days are longer and temperature is warmer.

                        iii.       In the southern hemisphere this is reversed.

4.         Surface of the Earth

            a.         Water holds a lot of heat and requires a large amount of energy to change its temperature.

            b.         When the sun is shining, the temperature near the ocean (or lakes) does not rise as quickly as it does inland.

            c.         At night, the water slowly loses the heat it absorbed during the day so the temperature stays warmer.

            d.         In summer, the water absorbs heat, preventing the air from heating up while in winter the water releases that heat keeping the air warmer.

            e.         This keeps the temperature cooler in summer and warmer in winter than inland.

            f.         During the day, the air over land warms up faster than air over water.

            g.         As the air over land warms up it rises and cooler air from over water moves in to replace it. This is called the sea breeze.

            h.         At night the air over water stays warmer as the water releases the heat it absorbed all day. This air rises and is replaced by air over land. This is called the land breeze.

            i.         Mountains also determine weather.

                        i.         As air hits a mountain, it must go up and over it. As the air rises it cools and condenses, releasing precipitation. This makes the ocean side of a mountain very wet.

                        ii.        As the air comes down the other side of the mountain it is dry and cool. This makes that side of the mountain very dry.

                        iii.       In Canada, the western side of mountains is rainy while the eastern side is dry.

            j.         Humans can change local weather by constructing things out of brick, stone, concrete, asphalt, etc.

            k.         These materials absorb and hold heat, making cities warmer than the surrounding area.

Thermal inversion

•          Usually, warm air rises and so the air gets cooler as you move higher in the atmosphere.

•          The warm air is replaced by cooler air from the surrounding area.

•          Sometimes, a pocket of cool air sinks over an area and traps the warm air underneath it.

•          Because the air is trapped, pollutants are not carried away and can accumulate.

•          This causes serious air pollution and is a problem for people with asthma or other respiratory illness.