Margaret D. Andrews
Wind, air pressure, temperature, precipitation (rain, snow), humidity, clouds, and other phenomena make up what we call weather. Created by complex interactions of solar energy, water, air, and the motions of the earth, weather has a profound effect on our lives. It disrupts our plans, determines the abundance of our crops, influences the way we feel and act, and often changes the course of history. For these reasons and many more the forecasts of the weather are needed.
The Oceans play a major role in creating weather. Water evaporates from the surface of the sea, forms clouds and returns to the earth as precipitation. Warm water currents, such as the Gulf Stream, result in warmer climates wherever they come close to land. The temperature of the sea changes slowly, which moderates the seasonal temperature swings of coastal communities and gives them warmer winters and cooler summers than their inland neighbors. The difference in temperature between the sea and the land creates winds that blow toward the land in the daytime and toward the ocean at night. Warm, moist air blown over the cool surface of the sea can create low clouds, which we call fog.
Hurricanes are an example of a particularly severe weather condition that forms on the ocean. They usually begin over the tropical Atlantic when an area of low air pressure becomes encircled by a ring of extremely strong winds, often reaching speeds of over 160 kilometers per hour. The low pressure area and its surrounding winds move northward at about 45 to 90 kilometers per hour (25 to 50 knots). Since the path of a hurricane is primarily over water, there is little resistance to slow it down or moderate its winds.
The ocean responds quickly and dramatically to weather conditions. The wind creates waves and currents which mix oxygen into the water and stir up the bottom sediments. Wind and changing barometric pressure can raise the sea level and cause the flooding of shore areas.
Precipitation and evaporation can change the salt concentration of the water. Changes in temperature can generate vertical movements of water and are one of the most important factors affecting marine life.
Man’s relationship with the ocean is also influenced by the weather. High seas can sink ships, destroy waterfront property, and kill many people. Fisherman, waterfront resorts, and beaches may have good or bad seasons depending on the weather. Boat operators may get lost if they get caught in the fog. Strong winds may cause sailboats to tip over, and no wind at all can ruin a sailboat race.
Knowledge about the weather can make the difference between life and death to anyone on a boat. Weather also has many major effects on the marine environment.
Learning Activities
Make Your Own Barometer
Materials:
*tape
*scissors
*glue
*balloon
*small glass jar
*2 straws
*marker
*heavy rubber band
Stretch the balloon so that it covers the mouth of the jar and is flat on top. Wrap a rubber band around the mouth of the jar to hold the balloon in place.
Cut of the end of one straw at an angle so that it looks pointed. With the pointed end sticking out glue the other end of the straw to the center of the balloon piece.
Place the jar on one end of a heavy cardboard base and tape it down. Take the other straw and tape it in a standing-up position to a spot on the cardboard about a half inch from the pointer.
With a marker, draw a line on the straw where the pointer is pointing. You can label this with the date if you have room. This will be your starting point. As the air pressure changes, the straw will move up and down Watch you barometer from day to day. When the air pressure is high, it will press hard on the air in the bottle, and the other end of the straw will point higher. When the air pressure lowers, the air pressure in the bottle will push up, and the point of the straw will go down. If the pointer is higher on one day than the day before, the weather will be getting better. If the pointer is lower, the weather will be turning stormy.
Make Your Own Anemometer
Materials:
*3 straws
*2 or 3 twist ties
*4 foil mini-cupcake holders, 3 in one color and 1 in a different color
*tape
Cross 2 of the straws like a “+” sign. Wrap one twist tie around the middle to hold them together.
Tape the foil holders as close to the ends of the straws as possible. Make sure that the open ends are all facing the same direction.
Loop another twist-tie around the center of the four straws, leaving as long a tail as possible. Try to make the tail as skinny as you can.
Place the twist tie tail inside the unused straw. You should be able to blow near the foil holders and see your anemometer spin.
Take your anemometer outside with a friend. You can stick the straw in the ground or hold it in your hand. As it starts to spin, count the number of times the odd colored foil holder passes you in one minute. The number of turns tells how fast the wind is blowing.
