GFAwesome - Guide to the Data

GRUESOME!!


	Few fish care for their young, but the mouth-breeder does so by sheltering them in her mouth when danger threatens. She spits the young out when it is safe.

Guide to the Data

Data Glossary: What does it all mean?

The Weather Data
Numbers are meaningless without context, and occasionally the labels used to identify the different measurements may not be intuitively clear. To help make sense of the data, we have included a glossary of the data that the Global Forest Worldwide Weather Stations collect. The Weather Data
Time: The time that the row of readings was taken.
Inside Temp: This measurement is actually the temperature of the weather station's console, which was originally designed to be kept inside. Since our consoles are kept outside by the weather station these temperature readings are very similar to those for Outside Temperature.
Outside Temp: This is the temperature reading on the roof of the school at the time indicated.
Outside High Temp: The highest temperature in the half-hour interval of the reading.
Outside Low Temp: The lowest temperature in the half-hour interval of the reading.
THWSI: Temperature-Humidity-Wind-Sun Index. This index includes the effects of all of those factors to give the apparent temperature in hot weather. The THWSI is a similar measurement to Wind Chill Factor, but for hot days instead of cold ones! Please note that the Station only records the THWSI if the temperature is greater than 20 degrees Celsius.
THI: Temperature-Humidity Index. How hot it feels because of the humidity (this is like a simple version of THWSI). On our Stations, it is only recorded for temperatures greater than 20[degrees]C.
Solar Rad: Solar Radiation. A measurement of the sun's radiation reaching the earth's surface at the time indicated.
High Solar Rad: The highest recorded solar radiation in the half-hour interval.
UV Index: A relative scale of 1 to 16 indicating current UV intensity. 0-2 is Minimal, 3-4 is Low, 5-6 is Moderate, 7-9 is High, and 10+ Very High.
UV Dose: Each unit called a MED (Minimum Erythemal Dose) is the minimal light exposure necessary to create a reddening of the skin. This value is the result of including a "skin factor" and may therefore not be accurate for all people. To be safe, our stations are calibrated for very sensitive skin, i.e. 1.0.
Barometric Pressure: The weight of the air exerted on the station's sensor. Pressure changes are extremely important and useful for weather forecasting. For example, decreasing pressure is associated with thunderstorms and cloudy skies, while high pressure means clear sunny/starry skies. The weight of the air (atmosphere) will vary with altitude, so all barometric pressure readings are calibrated to the equivalent sea level pressure.
Wind Speed: The wind speed (km/h) at the time indicated.
High Wind Speed: The highest recorded wind speed (km/h) in the half-hour interval.
Wind Direction: Direction that the wind is coming from. For example a North Wind blows from the North.
Wind Chill Factor: ([degrees]C) How cold it feels with the wind.
Rain: The amount of rain (mm) that has fallen in a half an hour.
Rain Rate: The amount of rain that would fall in an hour if it kept up (mm/h).
Humidity: The relative humidity of the air. A percentage of the total amount of water that the air can hold. As temperature decreases, the air can hold less water, so there is much less water in the air in winter when humidity is 60% than in the summer when humidity is 60%.
Dew Point: The temperature at which the amount of water in the air reaches 100% Relative Humidity, and dew starts to form.

The Soil Data
Ground Air Temp: The outside air temperature at ground level. At some sites, the Hobo is buried under a snowpack for much of the winter, and the snow can insulate the ground air so that it can be much warmer than the air temperature measured by the weather station.
Soil Temp: The temperature of the ground changes more slowly than the temperature in the air. As a result it can be really cold out, but the roots of trees can still grow in the warmer ground.

Weather Basics
This section contains information that will be helpful for students writing their weather reports. Its purpose is to define and explain some of the terms used to describe certain weather patterns and phenomena. We hope that it will help in developing an understanding of the cause and effect relationship between the variables measured by the station and the weather that they see each day.
Air Movement: One of the basic principles of weather is that air is constantly in motion. Warm air rises, and cool air sinks. As air closer to the ground is heated by radiation being reflected by the earth's surface it begins to rise and is replaced by cooler air, which starts the process over again.
Air mass: A large shallow mound of air that is very horizontally uniform in temperature and humidity. You can think of an air mass as a blanket of air that covers an area of the earth.
Clouds: Clouds are one of the most useful and easily observable aspects of weather! Clouds tell us about temperature and wind, indicate good weather or an approaching storm. There are lots of different types of clouds and clouds can give us clues as to what is going on higher up in the atmosphere. Clouds form when the air cools down to dew point, and the water in the air condenses in to water droplets.
There are three main types of clouds. Cirrus clouds are high level clouds that appear feathery or curly because they are blown apart by winds as soon as they develop. Cumulus clouds are lumpy and puffy and usually have lots of water in them. Stratus clouds are spread-out, layered clouds, and are usually found in lower levels of the atmosphere. These three basic types are usually found in combination with one another. If clouds are found in the middle levels of the atmosphere 'alto' is included in their name, and if they are dark storm clouds they are called 'nimbus'.

Cloud Type	Description	Associated Weather
Cirrus	High level, long, thin, feathery	Fair
Cirrostratus	High, gauzy, a ring may form around the sun or moon	Fair
Cirrocumulus	Puffy groups resembling fish scales	Possible storms
Altostratus	Thick layer that almost hides the sun	Warm front. Rain to come
Altocumulus	Puffy with distinct edges. Resembles waves	May mean thunderstorm, nimbostratus clouds will follow
Stratus	Low and gray, may cover the whole sky	The weather is changing
Stratocumulus	Low broad lumpy sheets	Clearing weather
Nimbostratus	Low, Dark layer of clouds	A front is arriving, light or moderate precipitation
Cumulus	Puffy, often with a flat bottom	Light, brief showers.
Cumulonimbus	Very tall, dark base, may have an icy flat top	Heavy storms, violent winds. Indicates thunderstorms and possible dangerous weather

Front: Regions where two or more air masses meet. These regions are the greatest producers of weather disturbances and storms.
Radiation: Radiation from the sun is made up of light waves that have many different lengths. Some of these wavelengths are the visible light that we can see, some of them are UV radiation that can burn your skin, and still others are radio wave, microwaves, or infrared wavelengths. Some of these wavelengths make up the energy that heats the Earth and everything on it.
The main source of radiation on Earth is the sun but did you know that the Earth, water and clouds also emit radiation? They absorb radiation from the sun and when the air is colder than the temperature of the Earth, water or clouds, all these things lose heat in order to heat the air around them. The air actually doesn't absorb heat directly from the sun; when the air gets warm on a sunny day, it's because the ground has been heated up by the sun and is reradiating heat into the air. This is why it is warmer on cloudy nights than on clear ones - the clouds trap the heat released from the Earth and release a little of their own heat back towards the Earth!
The ground heats up three times faster than the water, and this is why it is usually warmer away from large bodies of water. If you are near an ocean or a large lake, there will almost always be a cool breeze coming off the water as the warm air over the land rises and cool air from over the water is sucked in under it.
Snow: New snow is generally fluffy and is made up of separate flakes or particles. Once the snow has fallen, it gradually changes into a denser, more solid structure known as the snowpack. The snowpack is made up of all the snow that has fallen during the winter. The structure of a snowpack varies with the amounts of snow or rain and temperature changes that make up the snowfall pattern. Snowpacks are both valuable and dangerous. Depending on the conditions of a snowpack, avalanches can occur, posing a threat to skiers and hikers. However, snowpacks provide cover for plants and animals in the forest, keeping the ground much warmer than the surface of the snowpack and preventing frost from penetrating far down into the Earth. When it melts, a snowpack provides much needed water to the forest and fills streams and rivers with spring runoff.
Thermals: These are columns of upward moving air that are heated by contact with the warm ground. Great for birds and hang gliders! If the air in a thermal is moist, it will condense as it rises and create big puffy cumulus clouds. If there is a lot of upward moving air, the energy created by the condensation pushes the clouds high up into the atmosphere and can create cumulonimbus clouds (also known as thunderheads.) If the thermal is over a large flat area, the upward movement can create dust devils or even tornadoes! For all this warm air that is moving upward, there is always the same amount of air moving in to replace it. That's why it gets really windy before and during thunderstorms!
Thunder and Lightning Storms: These storms develop from upward moving moist thermals. As the moist air cools, it reaches a saturation point (where the air contains as much water as it can possibly hold) and then condenses to form clouds, which are then pushed further upwards into the atmosphere by more rising air. It can take very little time for a cumulus cloud to develop that is tens of thousands of feet high. Cumulus clouds have a characteristic domed top because of this upward movement, and a flat base because at the bottom of the cloud, all the air condenses at the same level.
Once the cloud top is pushed up to the freezing level, the water droplets in the cloud freeze and from ice crystals. Once this happens, the crisp edges of the cloud will become fuzzy. The freezing process also triggers precipitation from the cloud - rain or hail. A thunderstorm can be made up of many of these thunderclouds, or 'cells', so while one cloud may only last for about an hour, a big 'multicell' thunderstorm can last for several hours. It is also possible to have many individual thunderclouds strung out in a line, creating a 'squall line'.
Lightning occurs because the water droplets and ice crystals moving to the top of the cloud carry positive electric charges, and the bottom of the cloud is left with a negative charge. The negative charge at the base of the cloud then causes the ground to be positively charged. So, there are two positively charged areas on either side of a negatively charged one. The difference in the charges increases as more and more water moves to the top of the cloud, and eventually the electricity will 'discharge' to try and even out the difference by exchanging charges between the positive and negative areas. These discharges are the lightning strikes that we can see, and the thunder that we hear is caused by the electricity heating the air suddenly and creating sound waves (similar to an explosion).
Lightning is actually made up of one stroke downwards, and then one or more return strokes that flash back up along the same path. It is the return strokes that we actually see. Lightning can strike between the cloud and the ground, or between the oppositely charged parts of the cloud. Cloud-to-cloud lightning (also called sheet lightning) occurs two or three times more often than cloud-to-ground (forked) lightning. Other kinds of lightning are heat lightning (far away cloud-to-cloud), ribbon lightning (created by strong winds moving the lightning as it flashes up and down), and ball lightning. It is also possible for electricity to discharge in the air without ever reaching the ground. This is called air discharge lightning, and it looks the same as forked lightning. This is more common in drier areas where the base of the cloud is much further from the ground.
We hear thunder after we see lightning because sound waves travel more slowly than light waves. This is how you can get an idea of how far away a lighting strike was by counting how long it takes you to hear the thunder afterwards. (Sound travels about one mile in five seconds, or about one kilometer in three seconds).