Despite all the fascination with the weather in our weather blogs, there is hard physics behind it that forms the basis of meteorology. Don’t worry, we don’t want to burden you with the Navier-Stokes equation, the “Ark of the Covenant of Meteorology”, or other differential equations. For our physical wind model, we simplify the flow conditions of the Earth’s atmosphere and make numerous assumptions that make our life easier (and also the blog author’s creation of formulas with the Word formula itor) 🙂
We consider the flow conditions purely
horizontally and assume stationarity, i.e. no change in spe over time. In addition, our flow field is horizontally homogeneous, i.e. isobars are always the same distance from each other.
This results in the Coriolis force and the pressure gradient force compensating each other. Since we also neglect friction, our wind model is only applicable above the friction layer of the Earth’s atmosphere.
We will omit the detail mathematical derivation here. uganda phone number library Ultimately, our assumptions result in the geostrophic wind. It is defin as:
Meteorological formulas to cut out and collect: The geostrophic
wind. On the right, the pressure field and the geostrophic wind. The drawing applies to the northern hemisphere.
Meteorological formulas to cut out and collect: The geostrophic wind. On the right, the pressure field and the geostrophic wind. The drawing applies to the northern hemisphere.
For our considerations, we ignore the Coriolis how to handle the most common sales parameter and the air density for the time being and from the above formula it follows that the geostrophic wind is perpendicular to the alb directory pressure gradient and always blows parallel to the isobars.
The pressure gradient always points in the direction of the greatest pressure increase, i.e. towards the high (see vector in the graphic above). The cross product of vertical vector k and pressure gradient us in the above formula can be easily reproduc by ourselves using the three-finger rule. In the northern hemisphere we use the right hand: the index finger points towards the high, the thumb points vertically upwards. The middle finger points in the direction of the geostrophic wind.
The three-finger rule us by our early shift forecaster in operational use. We are reassur that our weather center is still in the northern hemisphere. Image: MeteoSwiss.
