Bill-Alaska Geoscience: Atmosphere and culture

We live in an ocean of air, our atmosphere. Like our liquid ocean the atmosphere is also a fluid. It has currents of flowing air, exerts a pressure on the earth's surface(14.7 lb/sq in), and is divided into layers. The atmosphere is interconnected with the lithosphere, cryosphere, hydrosphere and biosphere. Any changes that take place in our atmosphere will also cause change in the other spheres. As western science gathers and analyzes more data, scientists now understand that our ocean of air and our oceans are directly tied to weather and climatic events. Yet with all of our scientific knowledge the average lay person cannot read the sky. The Inupiats and other native cultures were able to read the sky and make simple predictions without the aid of scientific equipment. They were able to recognize different cloud types and the type of weather associated with them. They also recognized weather patterns associated with the wind. If the wind blew from a certain direction or suddenly changed direction a change in weather would follow. To survive they needed to understand the sky and the clues it gave to help foresee changes in the weather. Other cultures throughout the world also were able to read the sky and link atmospheric patterns to weather. As weather patterns and climate changed so did the cultures of the people.

Cumulonimbus Badlands,SD..................................Mammatus Clouds Lincoln Co. Minnesota

Both skies shown above would have foretold stormy weather to the native cultures.

Today the native culture also use the technology to aid them in understanding weather. Bush pilots use their observations of the sky along with western scientific data to better understand weather. The weather determined the type of clothing used in various cultures and t

he types of food to be planted and harvested. Different cultures also created a variety of sayings or proverbs associated with the weather. Red sky at night sailors delight and red sky in morning sailors take warning is based on sky observations. Weather has influenced all cultures. Weather is part of myths and folktales, art, literature and has changed history. Photo on right shows clearing weather, red sky at night.
Our atmosphere is divided into layers. Each layer has different temperature and pressure gradient. All weather takes place in the troposphere. The atmosphere protects us from ultra violet radiation and through friction destroys most meteors. Through various instruments meteorologists can measure pressure, temperature, humidity, wind, and precipitation. With satellite technology we are able to monitor our atmosphere continuously. With all the data and new information we still cannot totally predict our weather. But we are able to give warnings to severe storms. Below is an F4 Wisconsin tornado from the summer of 2005.

Meteorologists are able to map the locations of weather fronts, low and high pressure systems and upper atmosphere weather like the jet stream. Weather is powered by the sun. The combination of water, air and the energy from the sun creates our weather. The steering force of weather systems is the jet stream. Circulation of air is caused by unequal heating of the earths surface. This unequal heating causes changes in air density. The differences in density allows warm air to rise and cool air to sink. The rising and sinking of air causes convection currents. These convection currents create land and sea breezes. Other winds are created from differences in pressure systems. Winds blow from a high to a low. The greater the difference between the pressure centers the stronger the wind. A low pressure system rotates counterclockwise and consists of less dense rising air causing cloud formations. A high pressure center is sinking air that rotates in a clockwise direction. High pressure is generally clear weather. Earth has large scale planetary winds created by unequal heating at different latitudes. The highest amount of solar energy is located at the equator heating the air causing the air to expand, lower the density and rise. As the air cools it sinks around 30 degrees latitude and returns to the equator. This convection current is a Hadley Cell. The planetary winds circulates air throughout the planet creating large highs and lows. Examples of planetary winds are the trade winds, westerlies, and polar easterlies. In different parts of the country large areas of the atmosphere develop the same temperature and humidity. These areas are called air masses. As the air masses travel they will collide with other air masses. Where two air masses meet a weather front forms. The two major fronts are cold and warm. At a warm fro

nt the warm air gradually rises forming cloud types that range from high cirrus to low nimbus. A cold front is dense air that plows into a warm air mass and forces up the air forming cumulonimbus clouds. These types of clouds can be an indication of severe weather. Approaching severe weather in Iola, Wisconsin, right.
The last ingredient of weather is water. Water cycles through the atmosphere releasing and absorbing heat. The process is the hydrologic cycle. In reality it is an energy cycle. The cycle consists of evaporation, condensation and precipitation. Evaporation is a cooling process while condesation is a heating process. To change liquid water to water vapor requires energy. In chemistry this is the latent heat of vaporization. This requires a tremendous amount of energy, 540 calories/gram of water to break the hydrogen bonds and change liquid water to water vapor. The reverse is true for the process of condensation, releasing 540 calories/gram of water into the atmosphere. Energy is also required to change to water to ice and ice back to water. The amount of heat required is the latent heat of fusion, which is 80 calories/gram. All changes of state either absorb energy or release energy.
Water and sunlight also create an atmosperic display that could have been used to predict precipitation, rainbows. A rainbow is created by the diffraction of sunlight through raindrops. If the rainbow is in the west is usually means approaching rain. If in the east it m

eans the preicipation has passed.

Double rainbow over Keatings Lake, Iola,WI.............Single rainbow

In the arctic there is a unique feature of the double sun dog on each side of the sun. The natives know that ice crystals are present in the atmosphere to create the display. At left a double sun dog over the tundra in Wainwright.

These sun dogs occurred during a high pressure system. The sky is clear with very cold temperatures. The sun dogs were on display during the daylight hours for three days. As the high pressure moved and was replaced by a low pressure system the display no longer occurred. Ice crystals in the sky also are seen as a halo around the moon . This phenomena

generally precedes precipitation. A problem in the arctic is how quickly pollutants can enter the ocean and atmosphere. Arctic haze is a problem that shows how the atmosphere is changing. Aerosols and other pollutants are showing up in brilliant red sunsets. As time goes on we need to study how the arctics atmosphere is changing. What forms of pollution and there sources must be studied. Our students need to understand that our atmosphere is

small compared to the total size of the earth. Our ocean of air is a thin blue line of life sustaining

gases and the source of our weather. The students need to understand the circulation of our ocean of air and how it relates to the science of meteorology. Using these digital resources the students can see first hand how weather relates to cultures and how western science studies weather and gathers data.