LissProductions.com Weather - Centennial, CO

WEATHER STATION

Weather Station - A weather station is a facility with instruments and equipment to make weather observations by monitoring atmospheric conditions to study the weather. This weather station has a thermometer for measuring temperature; barometer for measuring changes in air pressure; hygrometer for measuring humidity; anemometer for measuring wind speed and wind direction; and rain gauge for measuring precipitation.

What are heating degree days and cooling degree days?

Heating degree days are indicators of household energy consumption for space heating. It was found that for an average outdoor temperature of 65 degrees Fahrenheit, most buildings require heat to maintain a 70 degree temperature inside. Similarly, for an average outdoor temperature of 65 degrees or more, most buildings require air-conditioning to maintain a 70 degree temperature inside.

How heating and cooling degree days are computed?

Take the high and low temperature for the day, and average them. If this number is greater than 65 F, then we have (Average temperature - 65) cooling degree days. If the average temperature is less than 65 degrees, then we have (65 - Average temperature) heating degree days. Running totals are kept for these units over a time period of a year so fuel distributors and power companies can assess average demands.

Growing Degree Days

Growing degree day accumulations involve the amount of accumulated heat required for insects and their host plants to flourish. Growing degree days are those days necessary for these organisms to complete their growth and development. Insects are unable to control their body temperature and are dependent upon the temperature of their surroundings for warmth, thus the measure of temperature can allude to the existence of insects. The use of growing degree day (GDD) is becoming a more popular way to determine when to control insect pests that attack ornamental trees and shrub. It is hoped that accumulated growing degrees will become a guide in timing the application of a pesticide to control a specific pest more accurately. This information can also be very useful in monitoring landscapes for plant problems. The determination of growing degree days is very similar to that of the heating degree days used by a company selling home heating fuel to determine the schedule of the next shipment of fuel oil. GDD takes into account the average daily temperature accumulations, which influence insect development; providing an estimate of the insect's development based on temperature measurements. For each day that the average temperature is one degree above the base temperature, one degree day has accumulated. Due to temperature differences, insect development may vary from year to year and among locations in any given year; basing pesticide applications by a particular week on a calendar cannot take these variations into consideration. The formulation of GDD calculations is developed from a general base of knowledge inherent to the environment. The temperature at which growth starts for woody plants in the north-eastern United States is approximately 45 F t0 55F; to standardize the calculations used in determining a growing degree day, the base temperature has been arbitrarily set at 50 F. With this information, the calculations of the growing degree day for a 24-hour period require the following formula: Max. temp + Min. temp./2 -Base temp.(50)=GDD. For example: If on March 3 the maximum temperature is 60 and the minimum temperature is 50 the GDD for March 3 is 60+50/2 = 110/2 = 55F and 55F - 50F = 5 GDD. If the average temperature is equal to or less than the base temperature, no degree days are accumulated. For this system to work, the maximum and minimum temperatures need to be taken every day from March 1 to September 30. Early in the season the growing degree days will accumulate slowly; however, as temperatures rise they accumulate faster.

WIND CHILL

Wind Chill - The wind chill temperature is what the temperature "feels like" to people and animals during cold weather. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Once temperatures drop below 10°F and the wind is gusting, conditions are ripe for cold-related illnesses. Below -5°F, any wind is a major factor in frostbite and hypothermia.

HEAT INDEX

The Heat Index (HI) (or apparent temperature) is a measure of relative discomfort due to combined heat and high humidity. It was developed by R.G. Steadman (1979) and is based on physiological studies of evaporative skin cooling for various combinations of ambient temperature and humidity. As temperatures climb above 90 °F and humidity goes above 40 percent, conditions are ripe for heat-related illnesses.

HUMIDEX

Definition Humidex - Over the years, several measures have been proposed to relate various combinations of temperature and humidity into a single number to approximate what hot, humid weather feels like to the average person. Of these, humidex is the one most familiar to Canadians. Humidex was introduced into Canada in 1965. The index is a summer analogue of the wind chill factor in that it is an equivalent air temperature. Air of a given temperature and humidity is equated in comfort to air of a higher temperature that has a negligible moisture content. Comfort is quite subjective and largely dependent on the age and health of the individual. Weather conditions causing prickly heat in an infant may result in heat cramps in a teenager, heat exhaustion in a middle-aged and heat stroke in a senior. Humidex is also limited as an overall hot-weather comfort index because it does not consider other factors such as pressure, wind speed, precipitation, sunshine or pollen.

SEVERE WEATHER

The hottest day recorded in Colorado was July 11, 1888 when it hit 118° in the town of Bennett (Latitude 39.76 & Longitude -104.43 at 5,484 ft above sea level)

BAROMETRIC PRESSURE

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. Barometric pressure changes with local weather conditions, making barometric pressure an 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, 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.

METAR

An Acroymn for METeorological Aerodrome Report. It is the primary observation code used in the United States to satisfy requirements for reporting surface meteorological data. Minimum reporting requirements includes wind, visibility, runway visual range, present weather, sky condition, temperature, dew point, and altimeter setting.

ADVISORIES

A statement generally provides additional or follow up information to an existing weather condition. An advisory is for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property. A watch is used when the risk of a hazardous weather event has increased significantly, but its occurrence, locations, and/or timing is still uncertain. It is intended to provide advance notice of possible inclement weather. A warning is used for conditions posing an immediate threat to life or property. Depending on the type of warning, you should take immediate, appropriate action.

CLOUD HEIGHT

The cloud height on this site is an estimate of cumulus clouds using a formula based on temperature and dew point. Actual measurements of cloud height are made with a Micropulse Lidar (MPL). This device fires a laser into the sky and measures the backscattered signal. Costs for such a device are beyond the scope of weather hobbyists.
You can use the following formulas to calculate the height (H) of a cumulus cloud base given surface temperature and dewpoint.

A) H(meters)=125*(Tc-Tdc)

B) H(feet)=222(Tf-Tdf)

Note: 
A) Tc and Tdc in formula are temperature and dewpoint in degrees Celsius. 
B) Tf and Tdf in formula are temperature and dewpoint in degrees Fahrenheit.

RAIN FALL

"Measurable rain" refers to a rainfall total of 0.01 inches or greater. When you hear the terms "isolated" showers or "few" showers (10-20%), "scattered" showers (30-50%), or "numerous" showers(60-70%), in the forecast, this refers to the percent of the forecast area covered by measurable rain. For instance, "scattered showers" means that the forecast area WILL receive rain, and approximately 30-50 percent of the area will experience showers.

DEWPOINT

Dewpoint is the temperature to which air must be cooled for saturation (100% relative humidity) to occur. 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 vapor content; low dew point indicates low vapor content. In addition a high dew point indicates a better chance of rain and severe thunderstorms. You can even use dew point to predict the minimum overnight temperature. Provided no fronts or other weather pattern changes are expected overnight, the afternoon's dew point gives you an idea of what minimum temperature to expect overnight. 

SEVERE WEATHER

The coldest day recorded in Colorado was on Feb 1 1985 when it hit -61°F in the little town of Maybell (Latitude 40.52 & Longitude -108.09 at 5,920 ft above sea level)

HUMIDITY

Humidity or relative humidity measures the amount of water vapor in the air relative to the temperature. It is important in weather because humidity affects how humans feel. A hot, humid day feels hotter because we cannot sweat as effectively. A cool, dry day feels colder because moisture evaporates more easily

RAIN FALL

Terms such as "slight chance" of rain (10-20%), "chance" of rain (30-50%) or rain "likely" (60-70%) are used when there is uncertainty of receiving measurable precipitation anywhere in the forecast area (such as the Greater Phoenix Area). For instance, if there is only a 30-50 percent chance that rain will fall anywhere in the Phoenix Metro area, then the forecast will call for a "chance" of rain.