Learning standards met: Investigate causes a of severe weather, use of weather maps, read and interpret weather data, development and dynamics of climate change
Why we care about weather Discussion for Earth Science, Ecology, Ecosystems, weather and climate involve energy transfer
Weather impacts our daily lives. Our weather determines if we wear a heavy coat or a T-shirt, if we go swimming, or sledding. It also determines if we need to restrict our water use, or evacuate from a flood. Weather can leave us with storm damage to our home, or a beautiful day to play outside. What causes weather?
Let's look at what makes wind on Earth…
Model: A balloon can be used as a model of wind between high and low pressure. A deflated balloon at rest is a balloon filled with air at equilibrium with the atmosphere. Blow air into the balloon, inflating it. Hold the open end closed. There are now more air molecules in the balloon than there were at equilibrium. The balloon is compressing the air, so there is higher pressure inside the balloon than there is on the outside. If the opening is opened a bit, the air will rush from the high pressure in the balloon to the lower pressure area outside the balloon. This is similar to the way wind works. In the atmosphere, air seeks equilibrium. Air moving from areas of high to low pressure creates wind. The greater the temperature or pressure difference between air masses, the stronger the wind as air rushes from one to the other. The rotation of the Earth on its axis directs some of the wind around the areas of high and low pressure, creating a swirling effect of the wind, so that the high and low pressure areas are circular. These are called high and low pressure "cells."
Where does rain and snow come from?
Water evaporates from oceans, lakes, and moist soil, and rises on warm air currents. When it reaches high up in the sky, the water condenses into clouds. The warmer the air, the more evaporation can occur, because warm air holds more water than cool air. When winds cause cool air to collide with warm moist air, the water-laden air cools, and rain or snow falls.
Our day to day weather is dependent upon many things including air temperature, winds, humidity, time of year, and where we live on the planet. The climate of an area is the long term trend of the weather pattern. We expect it to be colder in Alaska than in Maryland, and warmer near the equator than in Maryland. (That's climate.) But on any given day it might be cooler or warmer or wetter or drier in any one place. (that's weather).
We now know that the climate patterns around our planet are beginning to change. The entire planet is warmer than it once was. This is caused by an increase in greenhouse gases, such as carbon dioxide and methane, which strengthen Earth's natural greenhouse effect.
How do we know what is natural and what is caused by human activity? Scientists have 140 years of data on climate to look at. From that they can compare the sun's energy output over time, the impact volcanoes have had, land use changes and the urban heat island effect as well as measured carbon dioxide from combustion both natural in the form or forest fires and that that is human caused. If you rule out the impact of what is natural, you are left with humans as a cause unless someone finds some new information.
A warmer planet causes greater evaporation and warmer air will be able to hold more water. With a warmer planet, there will be more water in the atmosphere, leading to more intense rainfall or snowfall in storms. Also added heat in the oceans will create more energy for hurricanes, meaning there will be more powerful hurricanes. With global warming, more days of extreme high temperatures are expected around the planet. Extreme high temperatures with high humidity often lead to thunderstorms, like those we experience regularly here in summer months but they will be stronger. So far, scientists are unsure that we can say that climate change has already caused an increase in frequency or intensity of storms, but it is what we should expect with global warming. Remember climate is a long time, and we have only been taking measurements a short time. Compare stronger climate change caused storms to dice that are weighted, but just a little on one side. Normal chance says any combination is possible, but the slight weighting means one set of numbers will come up more often. So strong storms are a process of chance, but some of them may be caused by global warming.
Global warming will change the patterns of temperature, rain and snow around the entire planet. However, we are unsure exactly what kind of weather in exactly what place is likely to happen as the climate changes. We can expect unusually heavy snowfalls in some areas, as the warmer (not warm, but warmer) air in winter can hold more moisture as well. Though we can expect storms generally to be more intense, some places will not get as frequent rain or snow as they once did. This is very important, because rain and snow are how we get water to use for daily living. Imagine not being able to fill swimming pools or get a drink because of drought. With global warming, this could happen as well.
A link with printable material on reading weather maps, grades 6-12 is at http://www.teachervision.fen.com/weather/teacher-resources/6675.html
Reasons we should try to slow climate change: Learning standards met: numbers sense, patterns and relations, data analysis, ecology,
There is geological evidence the climate of Earth has changed many times, and sometimes in as little as 100 years. Scientists are still trying to find out why this has happened, but they have evidence of the impact. Can entire classes of animals and plants become extinct because of climate change? The evidence would suggest that they can. We have no control over volcanoes and some natural processes that release greenhouse gasses. We do have control over our individual release of greenhouse gasses which impact weather, the oceans, and climate.
Each species on Earth has a limited tolerance for gasses in the atmosphere, pH of rain and ground water, and temperatures. People are adaptable, but we too have limits, and we depend for our survival on many species that are not as adaptable. Would you want to live where the summers temperatures are over a hundred degrees and there is no water? Would you want to live where the temperatures are below freezing six months a year because that is where there is water? Would you want to live without fish or roses because they could not survive climate change?
A rapid change in climate will impact our water supply as glaciers disappear, rivers and reservoirs dry, and salt water moves further inland replacing fresh water, contaminating ground water. An increase in carbon dioxide in the air will dissolve into the oceans to change their pH making them more acidic. This would affect shell fish visibly and stress other marine life. Many countries depend for the bulk of their protein on marine fish. Storms will become more severe and rain patterns will change, so rain and snow may not stay on the land feeding rivers, lakes, and ponds. It may not fall as often and may not fall on the land at all, increasing drought and farm failure. The change in hydrology ( water patterns of distribution ) has already been linked to increased forest fires and erosion in North America.
Global warming will impact what insects we live with and what diseases or crop failures they might bring. Insects adapt well to changes in temperature, but most can not tolerate freezing. A warmer Earth will see an increase in certain types of insects.
Climate will impact where our food grows and what food we will be able to grow. Our foods may have to change. As rainfall and temperatures change, the foods we eat will have to change. Agronomists are already looking at what crops we may be able to produce in quantities that can feed the population. Wetland plants, like cattail, lotus, and paw-paws may become the foods we see in the groceries.
Climate change will impact the severity of storms, making heavier snow or high winds, more common. This is likely to increase damage to human structures and activities. It will impact where we live and how we live. If the Earth continues to warm, sea levels will rise because warm water expands and glaciers will melt adding water to the ocean. More people will have to live together on reduced areas of land. This will impact how much land we have for farms, recreation, and homes. It will impact tides because warmer water is less dense and so it rises. Higher tides will wash away wetlands, beaches and erode the land.
Global warming is one factor which will have a major impact on the diversity of plants and animals living on the planet. Reduced biodiversity will reduce our options and the choices we have for all aspects of our life.
Things we can do to slow climate change:
We can try reduce our carbon footprint by walking, riding bikes, and taking public transportation, instead of using a car to go everywhere.
When we do need to use a car, we can use a car that uses less energy.
We can turn off lights, computers, televisions, and other electric appliances when we are not using them. Generating electricity often produces greenhouse gases. We can open shades on the sunny side of our homes in winter to get the solar heat and close them in summer to keep heat out.
If you have a home you can plant evergreen trees on the north side of the house to reduce heating needed, and deciduous trees on the south side of the house to reduce cooling needed.
We can share what we know about climate change with others. Talk to your parents about buying energy efficient appliances when they can.
We can plant and take care of trees and protect the water. Trees and the plants in the ocean and estuaries absorb carbon dioxide from the air. Carbon dioxide is a major greenhouse gas. However there are limits to how much carbon these plants can absorb in their lives. As they decay, they will release that carbon,
We can recycle cans, bottles, plastic bags, and newspapers. And we can use products that have been recycled. It usually takes less energy to make recycled products than to make new ones.
Did You Know?
Washington DC is is the middle of the Chesapeake Bay watershed. Trash and balloons from the neighborhood or park go from the streets to the Bay and oceans where it may kill marine life. Do your part to keep litter in its place. More...