Upward motion of condensed water droplets in still air

Source: “Will rising water droplets change science?” by C. K. G. Piyadasa, 2011, Canadian Journal of Pure and Applied Sciences, Vol. 6, No. 2, pp.1995, Reprinted by permission of SENRA Academic Publishers, 5919 129 B Street Surrey, British Columbia, Canada V3X 0C5.

• Thermal image reveals that there is no significant increase in temperature below the turning point (Figure 1), by thermal radiation from heated water droplets moving above.
• A decreasing temperature gradient (Figure 1(c)), instead, is found. Such does not support upward movement of either gas or liquid according to the current knowledge of convection. 

Important points to mention related to fundamental aspects of upward motion of water droplets due to convection currents

1. No air molecules can exert pressure on water droplets: Pressure exerted by air molecules would affect water droplets if average dimensions of the latter suffice a condition.  Pressure is a continuum property.  In practice, the average dimension (d) of the area affected by pressure has to be larger than at least 10 times the square of the mean free path (λ) (Michael, 2013) e)) of air molecules, i.e. d > 10 > λ²   In the case of convection current, the upward thrust by air molecules act on horizontal cross-section of water droplets.

The average dimension (diameter in this case) of a water droplet due to condensed steam at room temperature of 30°C and relative humidity around 70% is around 10µm (Piyadasa, 2012).   The mean free path of air at atmospheric pressure and temperature 30°C is approximately 65 ηm (Jennings, 1988).  The minimum average length d (i.e., ) of the area required to be affected by pressure is equal nearly to 42.3 µm.  Water droplets that we consider in this experiment, however, are around 10 µm in diameter, which is much smaller than the minimum dimension that should prevail to be affected by the pressure due to molecular motion of air convection.  Air convection, therefore, cannot affect water droplets even if convection currents do exist.

2. Momentum transfer from air molecules to water droplets is impossible: It has been proven that, even if updraft does exist, it is not possible to drive water droplets upwards in mid-air by energy transfer (momentum transfer) from air molecules to water droplets; the only fundamental mechanism in energy transfer in classical mechanics.  Consider the facts:

• Mass of a 10 μm water droplet =          5 × 10^-6 kg
• Mass of an average air molecule =          8 × 10^-26 kg

Mass of a 10 μm water droplet is, hence, 10²⁰ times greater than average mass of an air molecule.  It is thus clear that according to ‘Newton’s Third Law’ momentum (energy) transfer from air molecules to water droplets is impossible in quantities sufficient to stop downward projected water droplets (condensed steam) from the spout and turn around to move upwards!  In this collision, according to classical mechanics, hardly any kinetic energy/momentum is transferred to water droplets from air molecules (calculation in (Piyadasa, 2019) Appendix B).

It is clear from the above three arguments, that:

1. No convection currents occur at TAP,
2. Cross sectional areas of the water molecules are not sufficient to experience a pressure force from air molecules due to mean free path
3. Momentum transfer between water droplets and air molecules shows that there is hardly any energy/momentum transferred.