<p>The Coriolis Effect occurs in all directions equally, even straight zonal (east-west) winds.  </p>

<p>Many indeed struggle with this idea - <a href="https://physics.stackexchange.com/questions/43124/is-there-an-intuitive-explanation-for-the-southward-force-caused-by-the-coriolis">this Physics SE question</a> has a fair explanation as to why.</p>

<p>As arkaia commented, the total deflection magnitude is $f=2{\omega}\cdot{\sin(latitude)}$, which is an orthogonal vector change (and as such shows up as terms in both the <a href="https://en.wikipedia.org/wiki/Primitive_equations#Forms_of_the_primitive_equations" rel="nofollow noreferrer">zonal and meridional velocity equations</a>).</p>

<p>So there's still deflection to the right (in the NH) equally regardless of which direction the air/water is flowing (except that in such a feature, deeper water is moving slower, so deflects by less magnitude... but still matching in regards to the proportion in comparison to the velocity).  Otherwise the result would not be <a href="https://en.wikipedia.org/wiki/Ekman_spiral" rel="nofollow noreferrer">a spiral</a>... but only at most a 90° decaying curve, since as the water begins to turn towards a more zonal direction, the angle of deflection would start to decrease, until at some height the water is moving easterly (or westerly) (such as at height labeled 3 in <a href="https://en.wikipedia.org/wiki/Ekman_spiral#/media/File:Ekman_spirale.svg" rel="nofollow noreferrer">this diagram</a>), and the water below it wouldn't turn further.  So the direction independence of Coriolis is vital to there being Ekman spirals at all.</p>

CC BY-SA 3.0
2018-01-31T16:17:18.790Z
The only place that has zero Coriolis if you are going along a latitude line is exactly at the Equator
arkaia
CC BY-SA 3.0
2018-01-31T16:14:12.587Z
2018-01-31T17:39:15.873Z
2018-01-31T17:39:15.873Z
JeopardyTempest
<p>I am in a Marine Environmental Science II class, and we are discussing the Ekman Spiral. As I understand, the Coriolis Effect does not occur when whatever is observed does not change latitude. So, if a wind above the ocean in the Northern Hemisphere were to hypothetically blow due East, with no change in latitude, would the water under the wind still be deflected to the right in the form of the Ekman Spiral?</p>

<p>Thanks in advance!</p>

CC BY-SA 3.0
2018-01-31T15:50:09.230Z
The Coriolis effect acts even if you do not change latitudes. f=2*omega*sin(latitude), where omega is the rotation speed of the Earth (one rotation in about a day).
arkaia
CC BY-SA 3.0
2018-01-31T16:17:32.663Z
The only place that has zero Coriolis if you are going along a latitude line is exactly at the Equator
arkaia
<wind><ocean-currents><coriolis>
If a prevailing wind traveled due east in the Northern Hemisphere, would the Coriolis Effect act on the water?
Ben Hunt
# If a prevailing wind traveled due east in the Northern Hemisphere, would the Coriolis Effect act on the water?

(Asked by: username_0 on 2018-01-31)

I am in a Marine Environmental Science II class, and we are discussing the Ekman Spiral. As I understand, the Coriolis Effect does not occur when whatever is observed does not change latitude. So, if a wind above the ocean in the Northern Hemisphere were to hypothetically blow due East, with no change in latitude, would the water under the wind still be deflected to the right in the form of the Ekman Spiral?

Thanks in advance!

**Tags:** wind, ocean-currents, coriolis

> **Comments:**
> **username_1**: The Coriolis effect acts even if you do not change latitudes. f=2*omega*sin(latitude), where omega is the rotation speed of the Earth (one rotation in about a day).  
> **username_1**: The only place that has zero Coriolis if you are going along a latitude line is exactly at the Equator  

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## 1 answers

### Answer by username_2 on 2018-01-31. Score: 5

The Coriolis Effect occurs in all directions equally, even straight zonal (east-west) winds.

Many indeed struggle with this idea - [this Physics SE question](https://physics.stackexchange.com/questions/43124/is-there-an-intuitive-explanation-for-the-southward-force-caused-by-the-coriolis) has a fair explanation as to why.

As username_1 commented, the total deflection magnitude is $f=2{\omega}\cdot{\sin(latitude)}$, which is an orthogonal vector change (and as such shows up as terms in both the [zonal and meridional velocity equations](https://en.wikipedia.org/wiki/Primitive_equations#Forms_of_the_primitive_equations)).

So there's still deflection to the right (in the NH) equally regardless of which direction the air/water is flowing (except that in such a feature, deeper water is moving slower, so deflects by less magnitude... but still matching in regards to the proportion in comparison to the velocity). Otherwise the result would not be [a spiral](https://en.wikipedia.org/wiki/Ekman_spiral)... but only at most a 90° decaying curve, since as the water begins to turn towards a more zonal direction, the angle of deflection would start to decrease, until at some height the water is moving easterly (or westerly) (such as at height labeled 3 in [this diagram](https://en.wikipedia.org/wiki/Ekman_spiral#/media/File:Ekman_spirale.svg)), and the water below it wouldn't turn further. So the direction independence of Coriolis is vital to there being Ekman spirals at all.

> **Comments:**
> **username_1**: The only place that has zero Coriolis if you are going along a latitude line is exactly at the Equator  

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