Where to get weather elements

If there is not enough room to hold all the days of weather forecast we will use the CSS to hide the extra content.

Each day of the forecast is a set of HTML elements that correspond to a variable of the weather forecast. We are going to show five pieces of information for each day — the date, an icon which summarizes the conditions, the maximum and minimum temperatures, the expected rainfall and a little text summary of the conditions. To create and populate the above HTML, we iterate the forecast values which represent each day of the forecast. We add a new HTML structure for each day which looks like this:.

For temperature, location name and conditions, we can insert the weather forecast variable value directly into the appropriate div for the day with the minimum of formatting. In this case we rounded the values to remove unnecessary decimal points. Later we will discuss how the unit of measurement for each value could be added. The date, precipitation rainfall and conditions icon are a little more involved.

We then format the date to produce a Month-Date value. In the query, we requested that the result include icon codes for each weather forecast period. We use this value to select an appropriate icon using a CSS selector. If you run the page now, the weather forecast should be populated however it looks awful! We need to add some CSS to format it correctly. The first step is to arrange the days horizontally or vertically depending on the view we decided earlier.

This will allow us to add CSS rules that are conditional on the orientation. Three CSS selectors define the basic layout. When this is displayed in horizontal view, we use row-based flex layout and when it is displayed using the vertical view, we use column-based flex layout. Switching the order from horizontal to vertical is not enough to make an attractive forecast however.

We need to arrange the content within the day a little differently based on the view. For the horizontal view, the weather forecast elements are arranged vertically. We do this by specifying a grid layout with two columns. Most of the weather elements span both of these columns but the Maximum and minimum elements span one — left and right. Most of the weather elements span both of these columns but the Maximum and minimum temperature elements span one — left and right.

We now override this for our vertical view. The vertical view uses a horizontal display for each day. This horizontal view is a single row of cells so all of the elements use a single span cell. We add CSS rules to override the day arrangement when the forecast is displayed in vertical mode:. We should now have a relatively attractive weather forecast layout. The final thing we do is add a little bit of formatting to the elements. We now have our basic Weather Forecast display wired and displayed.

The forecast will refresh whenever the page is reloaded. Depending on the formatting of the container element, the widget will switch from a horizontal to vertical view. You can find the full code for this sample in the Github. There are some missing features that would be nice to add. The columns object is a map of all the available columns that are used in the data.

Each variable contains two very useful values — the variable full name and also the unit of measurement used for the value. Another feature that would be nice to add would be some more interactivity — for example if forecast days are hidden, add a way for the user to open the hidden days or maybe click on a day to retrieve the hourly forecast?

Finally, it would be great if we could take advantage of some of the more advanced features of the weather API. How about creating an infinite weather forecast that switches to use historical climate statistics to predict the weather more than 15 days out? Alternatively we could allow users to bring up historical weather data records in a similar forecast-style widget. Looking for a more complete widget?

We have released our first open source weather forecast widget. You can install it and read about how it was implemented. This unit will deal with the role weather plays in the start and spread of wildfires and in the use of prescribed Fires. There are several elements of weather that must be considered. They are:. Temperature Wind Stability of the atmosphere Relative humidity Precipitation Cloud development In addition drought , a result of certain weather conditions, must be considered.

Air temperature has a direct influence on fire behavior because of the heat requirements for ignition and continuing the combustion process. We discussed radiant heat in the previous unit. Heat from the sun is transferred to the earth by radiation. This heat warms up the surface of the earth and the atmosphere close to the surface is in turn warmed by heat reflecting from the surface. This is the reason that the temperature above the surface is cooler than at the surface of the earth.

These temperatures generally decrease about 3. This decrease is known as the adiabatic lapse rate. Forest fuels receive heat by radiation from the sun. As a result, less heat is required for ignition. The sun emits short-wave energy rays radiation. When striking a solid object such as trees or grass, it is warmed. The surface absorbs some of the heat and reflects some in long-wave radiation that is absorbed by the water vapor in the air thus raising its temperature as well.

Arguably, temperature, is the single most important weather factor affecting fire behavior. Some might say that relative humidity is most important but we will learn that temperature drives relative humidity.

Warm fuels will ignite and burn faster because less heat energy is used to raise the fuels to their ignition temperature.

Fuels exposed to sunlight will be warmer than the fuels in shade. They will also be drier. For this reason, fuels not shaded by an overstory will generally be warmer and drier resulting in a more intense fire. Fires also burn more intensely in the afternoon. The temperature is the highest at that time resulting in higher fuel temperatures. Consequently, less heat is needed to raise the fuel to its ignition temperature. At the same time rising temperatures result in decreasing relative humidity and fuel moisture.

The type of surface will also affect the temperature. The temperature at the surface of a body of water will be cooler because the heat will readily penetrate and spread throughout the water. On the other hand, bare soil will be higher because heat will not penetrate. Instead, it will be concentrated at the surface.

In forested areas, the trees will absorb most of the heat. For this reason, fuel in the shade will be cooler than in the sun. We will be discussing other reasons later. Wind has a strong effect on fire behavior due to the fanning effect on the fire.

Wind can change direction and intensity throughout the day. This change can be very abrupt surprising the burner that is not alert. Abrupt changes generally occur during the afternoon when atmospheric conditions are most unstable.

We will discuss stability later. Wind is important to the prescribed burners fire fighter because of three influences it has on fire behavior:. Wind increases the supply of oxygen, which results in the fire burning more rapidly.

It also removes the surface fuel moisture, which increases the drying of the fuel. Air pressure will push flames, sparks and firebrands into new fuel. By pushing the flames closer to the fuel in front of the fire, the fuel is preheated quicker because of the increased radiant heat discussed previously.

More of the fuel becomes available for combustion since it is dryer and can reach ignition temperature quicker. In addition wind strongly influences prescribed fire smoke dispersal, a critical consideration. NWS also reports the transport wind speed, the average wind speed from the surface to the mixing height.

As a general rule prescribed burn planners prescribe surface winds at flame level or eye level between 1 and 5 MPH and transport wind speeds between 9 aqnd 20 MPH depending on the circumstance and prescribed burn objective. Air always moves as a result of temperature differences. It moves from high pressure areas to low pressure areas in an attempt to balance out the differences in temperature.

Due to the movement of the earth, this is not a straight line. Wind from a " high " will spiral outward in a clockwise direction in the northern hermisphere. The wind flow toward a " low " will spiral in a counter clockwise direction toward the center. These highs and lows are generally shown on weather maps. A weather front is the boundary layer between two air masses of different temperatures.

Fronts start from an area of low pressure. Winds will be the strongest at the frontal boundaries. Wind direction will also shift in a clockwise direction as the front passes. General winds are winds that are included in the weather forecast. Local factors will also affect the wind in an area that is too small to be included in the forecast.

These are known as " local winds ". There are two that are important to fire behavior in the southeast. Land and Sea Breezes. As discussed earlier, land surfaces become warmer than water surfaces during the day.

As a result, the air adjacent to the land surface, being warmer, begins to rise and the cooler air thus heaver flows inland to take its place. This local wind begins around 2 to 3 hours after sunrise and ends around sunset. At night, the reverse is true because the land surface cools more quickly than the water surface causing airflow from land to the water.

This shift generally occurs around 2 am. While these winds are normally strongest in coastal areas they may occur around large bodies of water. Eddy winds form around large objects and along tree lines. A ceilometer is a device that uses a laser or other light source to determine the height of a cloud ceiling or a cloud base from the ground. Ceilometers can also be used to measure the aerosol concentration within the atmosphere. A type of evaporation gauge or evaporimeter; it is a pan used in the measurement of the evaporation of water into the atmosphere over specified periods of time.

An instrument used to measure the humidity, or amount of water vapour in the atmosphere. The sensing mechanism of the instrument can be hair hair hygrometer , a plate coated with carbon electrical hygrometer , or an infrared sensor infrared hygrometer.

A hygrometer composed of two similar thermometers. The bulb of one thermometer is kept wet by means of a thin, wet cloth wick so that the cooling that results from evaporation makes it register a lower temperature than the dry-bulb thermometer. When readings are taken simultaneously, it is possible with the use of psychrometric tables to determine the relative humidity and dew-point temperature of the air.

An instrument which records the environmental temperature and humidity at the same time, usually both continually. A standard shelter for housing four types of thermometers: dry, wet, maximum and minimum. The screen shields the instruments from direct sunlight. A traditional thermometer consists of mercury, red spirit or green spirit in a glass tube and operates on the principle that the liquid expands more than the glass does when heated. Maximum temperature has historically been measured with a mercury-in-glass thermometer which has a constriction in the neck of the thermometer tube.

As the air temperature rises mercury is forced past the constriction. However, as the temperature falls the constriction prevents the mercury from returning to the bulb of the thermometer. The height of mercury in the tube remains at that reached at the hottest time of day. The thermometer is reset by gentle shaking. Alcohol-in-glass thermometers containing a moveable index are used to manually record minimum temperatures. When the temperature falls, the liquid and index move down the column, but when the temperature rises the index remains in the lowest position while the liquid expands up the tube.

The position of the index indicates the lowest temperature reached since the last reset - which is achieved by tilting the thermometer, bulb end upwards.