The observation that the smell of hot sizzling food travels further than the smell of cold food can be explained by several factors related to the nature of molecules and their behavior at different temperatures:

1. Rate of diffusion: During the process of cooking, the molecules in the food become energetic due to heating and start moving at a faster pace. The increase in molecular motion increases the rate at which these aroma-carrying molecules diffuse outwards into the surrounding air. Consequently, the smell passes and affects the nose at a greater distance.
2. Vapor pressure: Vapor pressure increases with higher temperature for most substances of interest. Volatile compounds that give the hot food its aroma have high vapour pressure at a higher temperature. These molecules have high vapor pressures, which make it easy for them to diffuse away from the food. Therefore, the smell is noticeable even from a distance because of this elevated vapor pressure.
3. Convection currents: When hot plates or pans are placed on a table, they create convective currents in the hot air resulting from them. They convey the odor molecules away upwards and away from the food source and help distribute the aroma over huge distances.
4. Sensitivity of our olfactory system: A stronger sense of smell towards some volatile compounds which are emitted could also mean that they were emitted at a relatively higher temperature. The aroma from hot food might therefore be detectable at a longer distance than the aroma of cold food due to this sensitivity.