Air Quality Services

Experimental Ventilation Forecast

Sample Experimental Ventilation Forecast

An experimental ventilation forecast is issued for Iqaluit. To see the experimental forecast, click here.

Air Quality and Weather

Weather conditions play a large part in the amount of air pollution we are exposed to at any given time. Atmospheric stability, along with wind speed and direction play a very important role. The following EC forecast products are used by air quality forecasters as guidance in the production of air quality forecasts.

Ventilation

The ventilation is and indication of the ability of the atmosphere to effectively provide “fresh air” over a given point. It is dependant on the mixing layer depth and the wind speed within the layer.

Areas with poor ventilation (under 2,500 square metres per second) are highlighted on the maps.

Wind Mileage

The wind mileage is an approximation of the distance a parcel of air would travel during the day if moved by the wind. The air quality will suffer in areas with low wind mileage values should these areas become polluted.

Areas with wind mileage below 200 kilometres are highlighted on the maps. Direction and speed of wind are plotted using a “wind barb” pointing in the direction the wind is coming from. The wind speed is shown by the barbs. Each barb represents 10 kilometres per hour, the half barbs 5 kilometres per hour and a filled triangle 50 kilometres per hour.

Mixing Layer Depth

The mixing layer is the atmospheric zone near the earth’s surface where pollutants disperse rapidly. The depth of this layer depends on the temperature and on the stability of the atmosphere at low levels. Lower values of mixing layer depth indicate that the pollutants will be mixed in a smaller volume of air.

Areas with a mixing layer depth of less than 400 metres are highlighted on the maps.