<p>Well, to start with, air does not strictly go from high pressure to low pressure. For example, in <a href="https://en.wikipedia.org/wiki/Geostrophic_current" rel="nofollow noreferrer">geostrophic balance</a> winds will move perpendicular to the pressure gradient.</p>
<p>Fronts form in a process called <a href="https://en.wikipedia.org/wiki/Frontogenesis" rel="nofollow noreferrer">frontogenesis</a>. To say that it is complicated might be an understatement. This process can be simplified into the <a href="https://www.weather.gov/jetstream/cyclone" rel="nofollow noreferrer">Norwegian Cyclone Model</a>. As an analogy, the cold air usually is the &quot;bully&quot; as it is denser. As the cold air is denser, it undertakes the warm air. Meanwhile, the warm air is less dense and rises over the cold air. Eventually the cold front catches up with itself, cutting off the warm air, causing an occluded front. With the lack of warm air to the center of the low, the frontal system slowly dissipates. There is a far more technical description, but for that, I would have to discuss vorticity advection, positioning of jet streak, etc.</p>

CC BY-SA 4.0
2022-10-22T15:35:03.057Z
@gansub The pressure gradient is perpendicular to the isobars. So my original statement is true. That is, the pressure gradient is perpendicular (really orthogonal) to the isobars. Air parcels move along the isobars in geostrophic balance. Therefore air parcels in geostrophic balance move perpendicular to the pressure gradient.
BarocliniCplusplus
CC BY-SA 4.0
2022-10-24T03:39:52.820Z
@gansub fixed‍♂️
BarocliniCplusplus
CC BY-SA 4.0
2022-10-21T01:55:10.710Z
2022-10-24T03:37:57.643Z
2022-10-24T03:37:57.643Z
BarocliniCplusplus
<p>I have spent hours on this topic and I seem unable to make sense of it.
If air moves from high pressure toward low pressure, and wind is the movement of air due to differences in pressure, how can, for example, a warm front occur? What can bring a warm air mass to overtake a cold air mass? Shouldn't just the cold air mass move toward the warm air mass, as the warm air mass has lower pressure and winds will be blowing in that direction?</p>

<meteorology><weather-forecasting><atmospheric-circulation><pressure><air>
Air pressure, fronts and temperature
Andrea Catarinella
# Air pressure, fronts and temperature

(Asked by: username_0 on 2022-10-19)

I have spent hours on this topic and I seem unable to make sense of it.
If air moves from high pressure toward low pressure, and wind is the movement of air due to differences in pressure, how can, for example, a warm front occur? What can bring a warm air mass to overtake a cold air mass? Shouldn't just the cold air mass move toward the warm air mass, as the warm air mass has lower pressure and winds will be blowing in that direction?

**Tags:** meteorology, weather-forecasting, atmospheric-circulation, pressure, air


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## 1 answers

### Answer by username_1 on 2022-10-21. Score: 2

Well, to start with, air does not strictly go from high pressure to low pressure. For example, in [geostrophic balance](https://en.wikipedia.org/wiki/Geostrophic_current) winds will move perpendicular to the pressure gradient.

Fronts form in a process called [frontogenesis](https://en.wikipedia.org/wiki/Frontogenesis). To say that it is complicated might be an understatement. This process can be simplified into the [Norwegian Cyclone Model](https://www.weather.gov/jetstream/cyclone). As an analogy, the cold air usually is the "bully" as it is denser. As the cold air is denser, it undertakes the warm air. Meanwhile, the warm air is less dense and rises over the cold air. Eventually the cold front catches up with itself, cutting off the warm air, causing an occluded front. With the lack of warm air to the center of the low, the frontal system slowly dissipates. There is a far more technical description, but for that, I would have to discuss vorticity advection, positioning of jet streak, etc.

> **Comments:**
> **username_1**: @gansub The pressure gradient is perpendicular to the isobars. So my original statement is true. That is, the pressure gradient is perpendicular (really orthogonal) to the isobars. Air parcels move along the isobars in geostrophic balance. Therefore air parcels in geostrophic balance move perpendicular to the pressure gradient.  
> **username_1**: @gansub fixed‍♂️  

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