• What is SIS Technology?

SIS Technology (TSIS) aims to control a set of phenomena (radiation frosts, odours propagation, dust propagation and radiation fogs) which occur in calm (windless) and clear (cloudless) nights and which effect on the activity or human life is often very negative.

TSIS arises from the application of advanced concepts in fluid mechanics and heat conduction to the lower layers of the atmosphere and to the ground in contact with them. This application aims to act on the mentioned phenomena to protect crops, in the case of frost; the welfare and health of the people in the case of odours and dust, and to safeguard the lives of those who travel on highways or use airport runways, in the case of radiation fogs.

TSIS has made ​​possible the development of two types of mechanical devices, the Selective Inverted Sinks (SIS) and the Jet-SIS.These devices are patented internationally and the application of them is exclusive of Frost Protection Corporation (more details on this website) and their authorized representatives.

• How does TSIS remove the odour perception in a populated area?

TSIS removes the odour perception in a populated area by diverting the course of the odour propagation, from the source that originates it (for example: sanitary effluents treatment plant) to the referred populated area.

• TSIS is capable of controlling any odour perception?

No, TSIS can only operate in cases in which odour propagation occurs in calm (windless) and clear (cloudless) nights and in the early hours of the day after the mentioned night.

• What is the propagation mechanism on which TSIS operates? 

The propagation mechanism on which TSIS operates is a type of wind called "katabatic wind" (KW). These KW are only presented in clear and calm nights on sloping ground and its intensity increases with the length of the slope. On these nights, anemometers located in meteorological stations (10 m above ground) usually indicate the absence of local or regional wind.

• What reach may the odour propagation have, when it is propagated by a KW? 

KW are originated starting from sunset anddisappear within a few hours from sunrise. The reach of the transportation performed by KW, rarely exceeds 20 km.

• How does TSIS operate to divert contaminated KW from its course?

TSIS operates placing Selective Inverted Sinks (SIS) and Jet-SIS in the course of the KW so that the contaminated fraction of it is selectively captured by the SIS and sent to the denominated "cloud of discharge” where odour will be content until sunrise. At sunrise, convective currents caused by the heating of the ground completely dissipate the "cloud of discharge”. That occurs without the air (with the contaminant already highly diluted) which arrived to this “cloud” during the night, return to ground level.

• How is it possible that the polluted air the SIS captures and raises to several tens of meters above the ground, doesn’t return to the surface of the ground where it was captured? 

Polluted air captured by the SIS is raised by these in a vertical jet that crosses several tens of meters of stratified atmosphere (see next question). On the other hand every jet, on its course, incorporates through its surface, air from the environment on which it travels. This causes a mixture, inside the jet of the SIS, of the air captured at the device suction with gradually warmer air coming from the strata that said jet goes through. As a result of the referred mixture, polluted air dilutes the contaminant concentration and increases its temperature. Due to this rise in temperature experienced by polluted air as it ascends, its descent becomes impossible since to descend it should go through the coldest strata and therefore denser, which separates from the ground the “cloud of discharge” where polluted and already diluted air arrives.

• What is a "stratified atmosphere"?

Under radiation frost conditions (clear sky, wind and fog absence) the soil loses heat through the atmosphere by radiation. The soil, which is colder than the adjacent air, cools the air, being this cooling process more significant in the lower atmosphere layers (first tenths of meters) and reducing its effect with height.

When the above described process occurs, in the lowest part of the atmosphere (closer to the ground) the well known “thermal inversion” is produced. That is very different to what happens during daytime, when temperature decreases with height.  Under radiation frost conditions, temperature increases with height in the atmosphere lowest layers.

Due to the fact that air density decreases with temperature, a stable organization of the atmosphere is developed (which does not change spontaneously with time) as the lower layers are the coldest ones and therefore the densest ones. Under these conditions the atmosphere can be ideally represented as a vertical succession of horizontal air “layers” or “strata” with increasing density towards ground. The referred process is called “atmosphere stratification”.