Lyndhurst-Hill Weather Station
Dayboro/King Scrub, Queensland, Australia

Wind

The anemometer measures wind speed and direction.

Temperature

The weather station houses a temperature sensor, the sensor is in a vented and shielded enclosure that minimises the solar radiation induced temperature error.

There are 3 types of temperature:

• Wind chill, takes into account how the speed of the wind affects our perception of the air temperature. Our bodies warm the surrounding air molecules by transferring heat from the skin. If there’s no air movement, this insulating layer of warm air molecules stays next to the body and offers some protection from cooler air molecules. However, wind sweeps that warm air surrounding the body away. The faster the wind blows, the faster heat is carried away and the colder you feel. Wind has a warming effect at higher temperatures.
• Heat index, The Heat Index uses temperature and the relative humidity to determine how hot the air actually “feels.” When humidity is low, the apparent temperature will be lower than the air temperature, since perspiration evaporates rapidly to cool the body. However, when humidity is high (i.e., the air is more saturated with water vapor) the apparent temperature “feels” higher than the actual air temperature, because perspiration evaporates more slowly.
• THSW Index, this is the Temperature/Humidity/Sun/Wind Index. The THSW Index uses humidity and temperature like for the Head Index, but also includes the heating effects of sunshine and the cooling effects of wind (like wind chill) to calculate an apparent temperature of what it “feels” like out in the sun. The THSW Index requires a solar radiation sensor.

Humidity

Humidity itself simply refers to the amount of water vapor in the air. However, the total amount of water vapor that the air can contain varies with air temperature and pressure. Relative humidity takes into account these factors and offers a humidity reading which reflects the amount of water vapor in the air as a percentage of the amount the air is capable of holding. Relative humidity, therefore, is not actually a measure of the amount of water vapor in the air, but a ratio of the air’s water vapor content to its capacity. When we use the term humidity in the manual and on the screen, we mean relative humidity.

It is important to realize that relative humidity changes with temperature, pressure, and water vapor content. A parcel of air with a capacity for 10 g of water vapor which contains 4 g of water vapor, the relative humidity would be 40%. Adding 2 g more water vapor (for a total of 6 g) would change the humidity to 60%. If that same parcel of air is then warmed so that it has a capacity for 20 g of water vapor, the relative humidity drops to 30% even though water vapor content does not change.

Relative humidity is an important factor in determining the amount of evaporation from plants and wet surfaces since warm air with low humidity has a large capacity to absorb extra water vapor.

Dew Point

Dew point is the temperature to which air must be cooled for saturation (100% relative humidity) to occur, providing there is no change in water vapor content. The dew point is an important measurement used to predict the formation of dew, frost, and fog. If dew point and temperature are close together in the late afternoon when the air begins to turn colder, fog is likely during the night.

Dew point is also a good indicator of the air’s actual water vapor content, unlike relative humidity, which takes the air’s temperature into account. High dew point indicates high water vapor content; low dew point indicates low water vapor content. In addition a high dew point indicates a better chance of rain, severe thunderstorms, and tornados. You can also use dew point to predict the minimum overnight temperature. Provided no new fronts are expected overnight and the afternoon relativehumidity is greater than or equal to 50%, the afternoon’s dew point gives you an idea of what minimum temperature to expect overnight, since the air can never get colder than the dew point.

Rain

The weather station incorporates a tipping-bucket rain collector that measures 0.2mm for each tip of the bucket. Here in Australia we reset the rain count at 9am every day. This means that the daily rain is calculated on the 24hrs period from 9am - 9am next day.

Barometric Pressure

The weight of the air that makes up our atmosphere exerts a pressure on the surface of the earth. This pressure is known as atmospheric pressure. Generally, the more air above an area, the higher the atmospheric pressure, this means that atmospheric pressure changes with altitude. For example, atmospheric pressure is greater at sea level than on a mountaintop. To compensate for this difference and facilitate comparison between locations with different altitudes, atmospheric pressure is generally adjusted to the equivalent sea level pressure. This adjusted pressure is known as barometric pressure.

Barometric pressure also changes with local weather conditions, making barometric pressure an extremely important and useful weather forecasting tool. High pressure zones are generally associated with fair weather while low pressure zones are generally associated with poor weather. For forecasting purposes, however, the absolute barometric pressure value is generally less important than the change in barometric pressure. In general, rising pressure indicates improving weather conditions while falling pressure indicates deteriorating weather conditions.

Solar Radiation

What we call “current solar radiation” is technically known as Global Solar Radiation, a measure of the intensity of the sun’s radiation reaching a horizontal surface. This irradiance includes both the direct component from the sun and the reflected component from the rest of the sky. The solar radiation reading gives a measure of the amount of solar radiation hitting the solar radiation sensor at any given time, expressed in Watts/sq. meter (W/m2).

Sunshine used interchangeably with the more precise term bright sunshine, when the sun casts an obvious shadow. The World Meteorological Organization defines sunshine as solar direct irradiance exceeding 120 W/m2.

Sunshine Duration

The length of time for which the sun casts an obvious shadow. The threshold tolerance for bright sunshine (based on World Meteorological Organization) is direct irradiance of 120 W/m plus or minus 20%.

UV (Ultra Violet) Radiation

Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV) rays. Exposure to UV rays can cause numerous health problems, such as sunburn, skin cancer, skin aging, cataracts, and can suppress the immune system. There are two way of displaying this:

• UV MEDs, MED (Minimum Erythemal Dose) is defined as the amount of sunlight exposure necessary to induce a barely perceptible redness of the skin within 24 hours after sun exposure. In other words, exposure to 1 MED will result in a reddening of the skin. Because different skin types burn at different rates, 1 MED for persons with very dark skin is different from 1 MED for persons with very light skin.
  
  Both the U.S. Environmental Protection Agency (EPA) and Environment Canada have developed skin type categories correlating characteristics of skin with rates of sunburn.

• UV Index, an intensity measurement first defined by Environment Canada and since been adopted by the World Meteorological Organization. UV Index assigns a number between 0 and 16 to the current UV intensity. The US EPA categorizes the Index values as shown in table belowThe lower the number, the lower the danger of sunburn. The Index value published by the U.S. National Weather Service is a forecast of the next day’s noontime UV intensity. The index values displayed by this weather station are real-time measurements.

Evapotranspiration (ET)

Evapotranspiration (ET) is a measurement of the amount of water vapor returned to the air in a given area. It combines the amount of water vapor returned through evaporation (from wet surfaces) with the amount of water vapor returned through transpiration (exhaling of moisture through plant stomata) to arrive at a total. Effectively, ET is the opposite of rainfall, and it is expressed in the same units of measure (inches, millimeters). This is calculated one a hour.

Leaf Wetness

Leaf wetness provides an indication of whether the surface of foliage in the area is wet or dry by indicating how wet the surface of the sensor is. The leaf wetness reading ranges from 0 (dry) to 15.

Soil Moisture

Soil Moisture, as the name suggests, is a measure of the moisture content of the soil. Soil moisture is measured on a scale of 0 to 200 centibars, and can help choose times to water crops. The soil moisture sensor measures the vacuum created in the soil by the lack of moisture. A high soil moisture reading indicates dryer soil; a lower soil moisture reading means wetter soil.

THSW

Temperature/Humidity/Sun/Wind (THSW) index, uses humidity and temperature like the Heat Index, but also includes the heating effects of sunshine and the cooling effects of wind (like Wind chill) to calculate an apparent temperature of what it “feels” like out in the sun.

Anthracnose (Colletotrichum graminicola)

Anthracnose can occur both as a foliar blight and a rot of the crown, stem base, and roots (basal rot). Anthracnose foliar blight typically occurs during mid-summer and attacks the leaves and stems of most cool-season turfgrass species. Particularly severe cases can develop on annual bluegrass fairways on golf courses. Anthracnose basal rot can occur during spring, summer, and fall and develops in the crowns, stem bases, and roots of annual bluegrass and creeping bentgrass, usually on golf course putting greens.

Anthracnose foliar blight appears as irregular yellow or bronze patches of diseased turf. Symptoms on individual plants first appear as yellow or red lesions on the oldest (outermost) leaves, then progress to a blighting of younger leaves and shoots. Occasionally, fungal fruiting structures called acervuli can be observed with a good quality hand lens on diseased leaves and stems. Acervuli resemble small, black pin cushions and are the location of spore production.

Anthracnose basal rot symptoms vary depending on the grass species affected. On annual bluegrass, symptoms appear as a bright yellowing of the turf in irregular patches. Affected bentgrass turf typically appears as irregular red or bronze basal rot, a dark brown or black color is present at the base of the plant. As the disease worsens, the darkening (rotting) progresses up the stem and acervuli can be observed with a hand lens on stem and leaf tissue.

Brown Patch (Rhizoctonia solani)

Brown patch is a major summer disease of lawns and golf courses. The most susceptible grass species include perennial ryegrass, tall fescue, and the bentgrasses. Occasionally, brown patch becomes a problem on Kentucky bluegrasses in mid- to late-summer during extended periods of high temperature and humidity.

On high-cut turf, patches may be up to several feet in diameter and circular. In early morning on dew-covered turf, white mycelium of the causal fungus can often be seen on and between grass leaves and stems in the patch. Sometimes, all the grass within the patch is killed, creating a sunken or "pocket" effect. More often, the turf in these patches is thinned rather than completely killed. Occasionally, no circular pattern can be seen, and disease appears as a diffuse blight.

On tall fescue, symptoms of brown patch can be observed on individual leaves and not necessarily in patches. Symptoms on leaves appear as irregular tan or light brown lesions surrounded by dark brown borders. In severe cases, the entire stand may look discolored and thinned.

Dollar Spot (Sclerotinia homoeocarpa)

On golf course greens cut at or below 3/16 inch, this disease appears as white or tan spots of dead turf about the size of a silver dollar. Hence the name dollar spot. On home lawns cut at 1 to 3 inches, dead areas may reach 2 to 4 inches in diameter. These spots may run together, producing large areas of dead turf. Affected leaves initially show yellow-green blotches, which progress to a light straw color with a reddish-brown margin. Occasionally, white mycelium can be seen covering affected leaves in early morning on dew-covered grass. Dollar spot symptoms occur anytime from early to late summer. The disease usually reaches peak activity when air temperatures are in the 80° F range and under high humidity. Symptoms also may appear in the fall. The most severe cases of dollar spot occur on turf receiving closely-spaced summer irrigation. The disease may also occur on nonirrigated turf when humidity is high from prolonged muggy summer weather. Dollar spot is more severe under nitrogen deficiency or when grass grows slowly.

Mildew (Erysiphe graminis)

his fungus first appears as isolated wefts of fine, gray-white, powdery growth on the upper surface of the grass leaf. This growth rapidly becomes more dense and may cover the entire leaf, giving the leaf a gray-white appearance. In severe outbreaks, entire portions of the turf stand may be dull white, rather than green. Individual leaves look as though they are covered with flour or white powder.

Fire Weather

Fine Fuel Moisture Code (FFMC)

The Fine Fuel Moisture Code (FFMC) is a numerical rating of the moisture content of litter and other cured fine fuels. This code is an indicator of the relative ease of ignition and flammability of fine fuel. It relates to the amount of moisture in a fuel particle that has no bigger diameter than 6 mm. Fine fuel moisture code (FFMC), 90 to 92 (82 to 96 for individual fires)

Duff Moisture Code (DMC)

The Duff Moisture Code (DMC) is a numerical rating of the average moisture content of loosely compacted organic layers of moderate depth. This code gives an indication of fuel consumption in moderate duff layers and medium-size woody material. Something like 38 to 78 (10 to 140 for individual fires)

Drought Code (DC)

The Drought Code (DC) is a numerical rating of the average moisture content of deep, compact, organic layers. This code is a useful indicator of seasonal drought effects on forest fuels, and amount of smouldering in deep duff layers and large logs. The drought code  210 to 372 (50 to 600 for individual fires)

Initial Spread Index (ISI)

The Initial Spread Index (ISI) is a numerical rating of the expected rate of fire spread. It combines the effects of wind and the Fine Fuel Moisture Code on rate of spread without the influence of variable quantities of fuel.

Buildup Index (BI)

The Buildup Index (BUI) is a numerical rating of the total amount of fuel available for combustion that combines the Duff Moisture Code and the Drought Code.

Fire Weather Index (FWI)

The Fire Weather Index (FWI) is a numerical rating of fire intensity that combines the Initial Spread Index and the Buildup Index. It is suitable as a general index of fire danger throughout the forested areas of Canada.

Radiation

Geiger Counter

Geiger counters are devices to detect and measure ionizing (nuclear) radiation. They are one of the oldest devices used to for this purpose, but are still one of the most sensitive, especially for the low radiation levels typically found in most situations.

The typical geiger counter consists of a metal body, called the tube, which is filled with gas at a low pressure. The gas usually contains Argon and Neon, along with small quantities of other gases (the quenching agent described below).

There is a second metal conductor, which is usually in the form of a thin wire, which runs inside the tube to a connector on the tube body. A high voltage, typically 500 or so volts, is applied between this conductor and the geiger counter tube body.

When a charged particle, such as an alpha or beta ray, or a gamma ray or x-ray, enters the geiger counter tube, it can hit one or more of the gas atoms, knocking off electrons. This process is called ionization.

The ionized gas is able to conduct electricity. In the case of the geiger counter, the applied voltage is high enough so that as the electric current flows, the electrons cause additional atoms to be ionized, resulting in even more current flow. In a very short amount of time, the feeble current caused by the radiation particle has grown to a larger current, which is easier to measure.

The quenching agent gas in the geiger counter stops the flow of electrical current after a few microseconds. Older geiger tubes used gases such as methane, which broke down each time there was a detection, resulting in a finite lifetime for the tube. Modern geiger counter tubes use gases that don't break down, resulting in essentially an unlimited lifetime for the tube, providing it is operated within the specifications and not subjected to physical abuse.

Each gas discharge event is measured and counted. Often, the number of events or counts per minute is recorded, resulting in the typical Counts Per Minute or CPM reading so often seen. Some detectors produce a click each time an event is detected. The higher the clicking rate, the higher the radiation level.

As weaker types of radiation are often not able to pass through the metal body of the geiger counter tube, often a thin window of light weight material is provided. The mineral mica is often used. Very weak radiation, even alpha rays, can pass though mica. The mica is of course more fragile than the metal, and must be protected from damage. Even just touching a mica window can cause permanent damage to the tube, as the window will usually immediately burst.

Geiger counter based radiation detectors have many advantages over other detectors, which typically use ionization chambers. They can detect very low levels of radiation - a single particle can be detected. Ionization chambers are only suitable for measuring large levels of radiation, a single particle of radiation cannot be detected. Geiger counters are also typically much smaller, as ionization chambers need to be quite large, due to their low efficiency in detecting radiation.

The geiger counter we use has detectors that use geiger counter tubes as the radiation sensor. The major difference between the various models is the sensitivity - the more sensitive units are capable of detecting smaller amounts of radiation and can detect all three types of radiation - alpha, beta, and gamma / x-ray.

Radiation

Each of our detectors contain one or more geiger mueller tubes, capable of detecting radiation. Each time a radiation particle enters the sensing window, it is detected, and the software on the attached computer is informed of this event. By adding up the number of detections per minute, the Counts Per Minute (CPM) is calculated and displayed in the included software. This number is a relative indicator of the amount of radiation present.

Typically background radiation levels will give you a 360 mrem dose per year (accourding to the National Council on Radiation Protectoin and Measurement), this would equivelent into 388768 CPM on our scale. The NCR limits are 5,000 mrem for radiation workers, 360 mrem for background this includes if you go for x-rays etc and 100 mrem if you are a hermit (like me) and do not leave the house.

Lets do some maths using the Co60 scale.

So how is this 360 mrem build up, what causes it, this is best to show via a pie chart.