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Energy and the Human Body Background Material
Measuring and monitoring weather
Climate | Weather watching | Avalanches | The sun Clouds and Percipitation | Wind
Where is weather created?
The troposphere is the layer of the atmosphere that is closest to Earth. It is approximately 10 kilometres in depth, where it meets the stratosphere. Each layer is identified according to its variations in temperature compared to height. For example, in the troposphere, the temperature decreases with height, and in the stratosphere the temperature increases with height. The whole atmosphere, from the troposphere to the exosphere, is only 700 kilometres deep. This mixture of colorless, tasteless, odorless gases is the only thing that makes the earth an excellent environment for life. Without it, we could not live here any more than we could on Mars or the Moon. The atmosphere is the source of the air we breathe, the warmth we feel, the protection we have from the sun's harmful radiation, the water we drink and our protection from meteorites.
How is weather created?
It is more intense at the equator and gradually less so towards each of the poles, where it is coldest. The difference in the temperatures in the various regions between the equator and each of the poles means that the air is warmer and colder to varying degrees around the Earth. Since warm air rises and cold air sinks, there are differences in air pressure in the troposphere, which causes continuous motion of the air. The movement of the air causes the constantly changing weather patterns on the Earth. The constantly moving air is actually the source of winds around the world. Hot air rises at the equator and falls at the poles where it is the coldest (receiving less of the sun's warmth). There are three different zones of circulating air between the equator and each pole. Within each of these zones, the air cycles as it is cooled and warmed. The places where these zones meet have some of the most turbulent weather. Except at the equator, powerful jet streams are created where these cycling masses of air come together and separate as they continue their cycle from lower to higher parts of the troposphere. Where the air is sinking (colder air), there is high pressure. Where the air is rising (warmer air), there is low-pressure. High-pressure weather tends to be clear and low-pressure weather tends to be cloudy, wet, and changeable. Meteorologists' knowledge of these systems, along with daily monitoring of local effects, allows them to predict weather. Air currents drive the weather globally, but there are other influences on the weather including the moisture content of the air. How much moisture air contains is a function of how close the air is to a body of water. This drives the formation of clouds and the resulting precipitation. Other geographical features that influence local weather variations include nearby mountains. Mountains can influence weather such as fog, Chinook winds and rain. Although these can be related to and do influence global weather patterns, a mountain's immediate weather influence doesn't necessarily apply to a large area. What is the difference between weather and climate? Climate - is the overall weather over time. It gives information about typical seasonal patterns, or patterns generally found in a large geographical area. We use this information to generalize and describe weather in a province, a state or a country over time. For example, people in the southern United States might generally assume that Canadians, especially those that live in Northern Canada, have very cold weather in general (which is true, in some areas especially), without taking into consideration that some summer daily temperatures can be quite warm, even comparable to some states. The climate is the average temperature, average rainfall, and so on.
Why do we measure weather and monitor climate? We measure weather because we are interested in knowing what the daily temperature is, and whether that temperature is normal according to the history of the climate for that area. We measure weather so that people can make daily clothing decisions, as well as plans about local and international travel. Weather and climate information is very important to those people who are planning vacations. Generally people don't want to visit tropical areas during the rainy season, nor do some people want to visit Canada in the height of winter. There is no way to know what specific temperature and precipitation you will receive for the specific days of your vacation, but you can choose dates that, according to climate information, are more likely to have warm weather and less likely to have an abundance of rain.
We measure weather and monitor climate (weather over time) for even more important reasons, including the safety of people. Based on weather monitoring and recording conditions that lead up to a hurricane or tornado and other potentially disastrous weather, we are able to predict when an area might be hit with such phenomena. The further ahead we know about these conditions, the more time people have to prepare their homes and property or even evacuate. By monitoring weather over time, we have also been able to learn about the effect that we, as humans have been having on our environment and we are learning about ways that we can make changes that are better for the environment. For example, the Greenhouse Effect is being monitored by measuring temperature and using climate data to compare temperature changes from historical to present time, especially since the industrial revolution. Atmospheric scientists and meteorologists measure, record and communicate weather patterns via weather maps, which are now usually electronically generated with computer technology in many formats. The ones used by meteorologists on your local news are simplified and interpreted by the news staff so that everyone can get the information they need from the report without knowing a whole lot about weather. To see more sophisticated examples, go to the weather website of your local news or government weather station and watch the weather news, especially the Weather Channel (in Canada).
Lines with bumps and/or spike-type symbols indicate where the air masses meet, which indicates where storms are occurring. The bumps represent warm fronts and the spikes (or triangles) represent cold fronts. One of the other major symbols shows wind direction as reported from various weather stations. These weather stations are indicated by a dot. A 'key' shape joined to the dot indicates the wind direction. The direction of the key is the direction from which the wind is blowing.
B. How Does Monitoring Weather Help the Everest 2000 Team? Climbers have to register their expeditions with the Nepalese government and receive permits for their permission to climb. There is no guarantee, however, on any given day that the weather will be suited to climbing during the 'climbing season'. In fact, the Everest 2000 team has to pay close attention to the daily weather reports that are specifically designed for climbers in the region. The detailed and specific weather information found in the Bracknell Report is key for making decisions about the progress of their expedition. Through daily weather reports and their own observations, the team may decide to wait before moving through the dangerous Khumbu Icefall, or may delay their summit attempt and wait out a potential storm at one of the camps. There is always a danger of avalanches that are often caused by variations in the weather that change the conditions of the snow. Though you cannot access the Bracknell Report report directly since there is an expensive fee involved, the data will be posted on the Everest 2000 website. You can use this information to monitor the team's progress and provide your own predictions and advice about decision making.
Why is it colder on Mount Everest and other high elevations than at
lower elevations? In the troposphere layer of the atmosphere, the temperature decreases the higher you go into its 10-kilometre altitude. The Everest 2000 expedition will be climbing to approximately 8,850 metres, or almost nine kilometres into the troposphere. This is almost 9/10 of the total altitude at which humans can breathe at all. In fact, anything past 7,904 metres is considered the Death Zone with high physical risk for even short periods of time.
At this altitude, not only is it colder than at lower altitudes,
but the atmosphere is thinner than it is closer to Earth. This
means that: (1) it provides less protection from the sun's harmful rays;
and (2) there is less oxygen per volume of air breathed in as a
result of the atmosphere being less dense per volume of air.
See the High Altitude and the Circulatory System section of the Energy & the Human Body Background Information for additional information on atmospheric conditions and effects on the Everest climbers.
C. Avalanche Information and Awareness
At the Canadian Avalanche Association (CAA) Website, you can find information on how to interpret avalanche bulletins that are released over the news or on the net. (This information may also be available at your local or national environment or weather monitoring service.) The CAA site even has a glossary of terms related to reporting and talking about avalanches. There are people whose careers are based in avalanche safety and snow science who would be good resources. Back country skiers, snowboarders, ski patrol members and high altitude mountain climbers are also good sources of information if you want to know more. An avalanche cycle is a period of avalanches that is associated with a storm or warm weather. There are different kinds of avalanches that are named according to how they were formed, as well as how they were set off. For example, a SLAB avalanche or a PILE avalanche.
D. Coping with the Sun on Mount Everest As a result of the high altitude, temperatures can also get as low as minus 46 degrees Celsius on the upper parts of the mountain (the troposphere decreases in temperature with height), but the sun's rays are even more of a danger at this altitude despite the cold.
WHY?
Since Mount Everest is 8,050 metres (29,035 feet) high, it is in the uppermost part of the troposphere layer of the atmosphere that helps to protect the Earth from the sun's UV rays. This means that a large percentage of the harmful rays that are filtered out gradually through the atmosphere at lower altitudes (where most people live) are not filtered on Everest. Climbers at this height are exposed to very dangerous levels of ultraviolet radiation. Also, 85 per cent of UV rays that do reach Earth (of which most are absorbed at lower altitudes) are reflected off the fresh, white snow, almost doubling the radiation exposure in this environment (Canadian Dermatology Association, Sun Facts). The sun's UV rays have the potential to be extremely dangerous for high altitude climbers, as well as for those people who live at relatively high altitudes on a year-round basis such as the Sheraps in the Mount Everest area of Nepal. Even more alarming is how little exposure is required to cause serious damage in a very short time. New research from the American Academy of Dermatology (AAD) can be interpreted to show that UVB levels are 29 times more intense at the summit of Mount Everest than they are at sea level. This means that a climber with an average complexion (neither extremely light nor dark) would develop serious sunburn in less than six minutes. In fact, the research says that the same person would sunburn after six minutes at only 11,000 feet (3,353 metres) compared to 25 minutes at sea level. These numbers are based on a clear day at noon in either location, with no UV protection such as sun block or protective clothing. You can read more about this research from the American Academy of Dermatology. With this kind of information, it is easy to see why climbers have to protect their skin from the sun's rays and the glare from the snow, which increases the intensity of the UV rays. This is just as important as protecting themselves from the extreme cold to avoid serious skin damage. With the sun there is the added danger of increasing your chance of developing skin cancer (Melanoma). People who live in higher altitudes and in areas where the ozone layer is thinning need to be educated by their local health organizations and governments to protect themselves from the sun more carefully. There is a major education program being conducted by the government of Australia, since its population of citizens has had dramatic increases in rates of skin cancer in recent history. This is due to a large number of fair complexions in an area that has the highest levels of solar radiation on earth. Also, human pollutants to the environment are damaging the ozone layer. There are places in the ozone layer that are either disappearing or thinning at an alarming rate, which is leading to compounding rates of skin cancer as a result of more UV rays (particularly more UVB) passing through the atmosphere to Earth. People burn faster than they did before with the same amount of sun exposure time.
The best ways to avoid skin damage and reduce the risk of
developing skin cancer include the following suggestions by doctors:
What is the difference between UVA and UVB radiation? UVB (ultraviolet B) - is responsible for sun burns, delayed tanning (the process continues in the skin after sun exposure is ended), aging, cataracts of the eye, and genetic damage that can lead to skin cancer. UVB rays are short wave radiation. They are the most powerful and potentially harmful, even though much of UVB is filtered out by the ozone layer in the stratosphere. The closer you live to the equator, or the higher the elevation, the more intense exposure is received. Other indicators for intensity of UVB exposure are time of day, season (winter has less direct sunlight) and cloud cover (dense, dark cloud cover does filter UV, though haze and light clouds do not). UVA (ultraviolet A) - causes immediate tanning and contributes to premature aging and possibly skin cancer. There are no regulations for UVA protection in sun block creams and lotions. The one to 15 ratings (and higher) indicate the level of protection from UVB. UVA rays pass through the ozone layer and until recently were considered to be harmless. The current status of this information is due to relatively recent studies. The waves of this radiation are longer than UVB and the exposure is virtually the same all year.
Why does the sun affect our skin the way it does - with suntans and sunburns?
It is made up of two main layers (with other layers within them), the outside layer being the epidermis and the inside layer being the dermis. Skin has many sensors, which makes it sensitive to heat, cold, pressure, itching and pain. Being sensitive is good for us because it warns us when something is damaging our skin. The part of the skin that we can see on the outside of our body is only the first of many layers of our skin organ. In fact, all we see is the layer of dead cells that make up the stratum corneum layer of the epidermis (or the outside part of our skin). The part of your skin that is responsible for the development of a suntan (or burn) is the malpighian layer of the epidermis. The epidermis has several layers within it. On the outside is the layer of dead skin cells that we see called the stratum corneum - what we call our skin. Then comes the malpighian layer, which contains the granular layer, the spinous layer and the basal layer. The basal layer of the epidermis is the last layer before the dermis layer. The basal layer contains melanocyte cells that produce melanin - the pigment that reacts to the sun to create a tan, and they are the cells that are responsible for melanoma, a form of cancer associated with sun exposure on the skin. All people have approximately the same number of melanocytes; the difference in the color of our skin is determined by how much melanin they produce.
What causes tans? Actually very brief exposure to sun for Caucasians builds protective melanin in your skin. Production of melanin takes quite a long time, but the brief exposure to UV rays is enough to stimulate the melanocytes into production of melanin which continues even after coming in from the sun. If you expose yourself very briefly to the sun for five to seven days, Caucasians can build pigment levels that are protective. The same cautious approach is not as necessary for races with dark skin since their skin produces melanin on a continuous basis, which provides more protection from UV radiation of the sun. This information however is only related to short exposure and as one of the ways to prevent burning. Any exposure to the sun, especially during 11 am and 4 pm will contribute to aging effects of the sun, particularly with prolonged exposure without proper protection including appropriate clothing and sunscreen.
What causes burns? When you get a sunburn you are experiencing damage at the cellular level. In reaction to this damage, the body increases blood flow to the skin to help repair the damage. The increased blood flow is the source of the redness and causes extra blood in the upper layers of your skin.
What causes melanoma or skin cancer? There are three main forms of skin cancer. They are:
How do sun blocks and sun screens work? The sun protection factor (SPF ratings) found on sunscreen and sun block creams and lotions indicates the product's ability to block UVB rays. Dermatologists advise that you choose a SPF factor of at least 15, regardless of your skin type. If you are very fair, you should seek higher SPF levels. For protection from UVA in your sunscreen, look for the term "broad spectrum protection". The product should also be approved by your national dermatology association. You may also contact your dermatology association for a list of approved sunscreens. Ingredients to look for are: Melanin - some producers are adding this to sunscreen, so that, just like the body, it will absorb the UV light, therefore blocking the skin from the UV. PABA (para-aminobenzoic acid) - is being used less in products now because of the high instances of allergic reactions. PABA filters UVB light. Titanium dioxide - blocks UVA and UVB. This is the type recommended for sensitive skin and high altitude exposure as a complete blocker of sunlight for the skin. A Calgary dermatologist has recommended the team use brands which are chemical free, meaning that they do not have a lot of other ingredients like moisturizers, etc. They are strictly used for the purpose of blocking the ultraviolet rays.
Don't we need the sun's ultraviolet rays for vitamins?
D. Cloud Descriptions and Helpful Hints for Identification
Basic Cloud Shapes:
Clouds occur at three altitude ranges (heights) in the sky. We judge the height of the clouds according to the base or bottom of the cloud and not the height (this is especially important for cumulus clouds). High Altitude Clouds:
1. Cirrus - 'Cirrus' being wispy and feathery at high altitude.
Middle Altitude Clouds:
4. Altocumulus - 'Cumulus' being puffy and heaped, but less dense in appearance than cumulus in a rippled pattern. There are also more spaces in the clouds so the sun is visible through them. NOTE: there are no middle range clouds with the prefix 'cirrus' or 'cirro' because Cirrus clouds are synonymous with high altitude clouds.
Low Altitude Clouds: 6. Stratus - Flat layered clouds, usually dull grey, which cover most of the sky, even blocking out the sun. They begin as a bank of fog that has risen higher than ground level. Any low altitude clouds that are dark, threatening rain or producing rain get the designation 'nimbus' or 'nimbo'. Cumulus and Cumulonimbus clouds have a base that starts at less than 2000 metres, but often grow tall enough to reach into the middle and sometimes high ranges. Only cirrus-type clouds are true high altitude clouds. They a base starting above 6000 meters. Extended Notes About Cloud Shapes: Cumulus means a heap or pile in Latin. These are white puffy clouds that look like giant bunches of cauliflower with flat bottoms. They are seen mainly in the summer on warm, sunny days. The sun warms the ground and huge bubbles of heated air rise into the sky. As with other clouds, the air cools, condenses, and in this case forms a cloud that is big and fluffy looking due to the cloud being formed with liquid versus ice crystals. Cumulus clouds reflect sunlight well because of the water droplets and they look very white. They are darker on the bottom because the sunlight gets filtered out more and more as it passes through these thick clouds, especially when they are at their largest. We generally don't see these in winter because it is too cold for the droplets to remain unfrozen. Cirrus means a curl or a tuft of hair (wispy) in Latin. These are feathery, wispy clouds with curled tails, like a horse's tail blowing in the wind. These are high-altitude clouds made the same way that all clouds form, but the water droplets are frozen to form millions of tiny ice crystals. They are often the first clouds to appear in a clear, blue sky. Stratus means a flat layer or 'stretched out' in Latin. These are dull grey clouds. They cover most of the sky and block out direct views of the sun. They often start as a bank of fog (low dense cloud) that rises higher in the sky.
How Do Clouds Form?
Warm air is pushed higher and as it rises and cools, this causes condensation, which forms clouds. Clouds, mist and fog are made of millions of water droplets of condensing moisture from the air. They can also be made of tiny ice crystals that form as a result of the cooling process happening more quickly, or to lower surrounding temperatures. Rain and snow, as well as freezing rain and hail are variations of the precipitation that falls from clouds depending on the conditions in which they form. The conditions are influenced by the geographic location, weather fronts, climate, season of the year, amount of moisture in the air that results in the daily temperature, and the occurrence, amount, and form of precipitation. Fog is a cloud up close. It forms close to the ground as a result of air currents and fronts. A cloud is exactly the same as the white puffs of air that we see when we breathe outside on a cold day. The warm air from our lungs contacts the cold air and condenses into water droplets, forming the visible white cloud of condensed air. The same is true of water vapor (the gas form of water once heated to the boiling point) as it escapes a pot of boiling water. The air in the room is cooler than the temperature in the pot and as the warm vapor hits the cooler air, it cools, condenses and forms what we call steam, which is a cloud. The most important factor that must exist to form a cloud is the amount of moisture in the atmosphere. If there is not enough water in the atmosphere then there can be no condensation into tiny droplets that form clouds. The water in the atmosphere comes from oceans, lakes and plants through the water cycle. Water in lakes and oceans evaporates, just as water left in a bowl for a period of time will eventually disappear. Water that plants draw up through their roots eventually evaporates through the leaves of the plants. It evaporates, rising as a gas into the atmosphere, but condensing as it begins to cool in higher altitudes to form clouds. The water droplets grow larger as more warm air condenses and eventually become too heavy to continue rising or to be held up by the rising warm air. At this point the water droplets fall in the form of precipitation.
Forms of Precipitation
Precipitation is in different forms depending on the altitude of the cloud. The altitude affects the temperature in the atmosphere and therefore the form of the water droplets that form the clouds. Another influence on the type of precipitation that forms is whether there are strong upward drafts of air inside the cloud. Rain is a water droplet in liquid form, usually in lower altitude clouds. Snow falls when clouds are in higher and colder altitudes, which causes the water vapor to freeze as it condenses to form ice crystals instead of water droplets that form the cloud. Sleet is rain that freezes as it is falling in cold temperatures. Freezing Rain is rain that freezes when it contacts the ground. Hail forms inside tall clouds with air currents blowing the water droplets up and down. Rain starts to fall inside the cloud, but it is caught by an upward sweeping wind and forced into a higher altitude. The drop of rain freezes in the higher altitude and falls, forming more condensation on it. It can be swept up again to refreeze, forming a larger hailstone. The size of the hailstone depends on the number of times this cycle repeats, which depends on the strength of the upward draft of wind in the cloud.
E. Wind Speed and Direction
What Causes Wind?
For example, picture what happens when you take a bucket of water out of a bathtub. There isn't less water in just that one spot. The remaining water distributes over the area of the tub with an even surface at the top. There is a lower level of water overall, but the water that remains is evenly distributed. When air warms, it rises. The air above land heats faster than the air above water because land absorbs more heat than water (water reflects more of the sun's rays). As a result, the air from the cooler area above water moves into the low-pressure area created by the rising warm air to equalize the pressure of the air. This movement of air to the area of lower pressure causes a breeze from the ocean, especially on a warm day. In the evening, the water is slow to lose the heat it stored up during the day (slower than the heat loss on land), so the opposite effect occurs. Air from above the land quickly loses its heat as the sun sets, and it is now cooler than the air from above the water. So, as the air above the water is warmed by the heat released from the water, it rises, creating an area of lower pressure than that of the air above the land. The land air moves in from the area of higher pressure to the lower pressure area causing an outgoing breeze from the land.
On a larger level, differences in air pressure are caused by differences in air temperatures, which causes air to move in patterns, which cause winds of various intensities. Breezes and winds do not only occur in places that are close to the water, but the basic principles are the same in terms of cold and warm air fronts rising, falling and moving. Cold and warm air fronts play a major role in temperatures and precipitation around the world. These world systems are in constant motion causing winds of various strengths and directions ranging from a very mild breeze to a dangerous hurricane.
Measuring Wind Speed - Beaufort Scale
You can tell that he was British by the wording of the descriptions in the scale. We still use this scale to describe the wind, but we also more accurately measure the speed of the wind now, providing more detailed and useful information for scientists. An instrument called an anemeter is the instrument used by weather scientists to measure wind speed. These are usually electronic now and computers convert electronic signals from instruments into digital displays. Beaufort Scale
To determine the direction of the wind, you can use a weather vane or a windsock. When describing the direction of the weather, you determine the direction that the wind is coming from and NOT the direction that it is blowing towards. So, if your weather vane's arrow is pointing north, the wind is a southerly wind (comes from the south and is blowing towards the north). If your windsock is pointing to the south east, then you are experiencing a north west wind. Davies, Kay. (1992). The Super Science Book of Weather. England: Wayland Publishers Ltd. Dickinson, Terence. (1988). Exploring the Sky by Day. Ontario: Camden House Publishing. Ward, Alan. (1992). Project Science: Sky and Weather. New York: Franklin Watts Inc. Mezger, Gabi. (1995). Weather Instruments: Teacher's Guide. New Hampshire: Delta Education Inc. Kary, Diana. (1996). Ready, Set, Science: Weather Activity Guide. Calgary: Science Alberta Foundation.
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