# Meteorology Physics: Apparent wind problem

• Sofina
In summary, the conversation was about a homework problem on Meterology Physics regarding a ship's Apparent Wind. The person had solved parts b and c of the problem but was unsure about part a. They proposed a solution where the particle is affected by both the Ship Wind and the True Wind at the same time, but the other person clarified that these are just different frames of reference and the particle is only affected by one at a time. The person also asked about the concept of ship wind and the other person explained it using an example. The correct solution for the problem is to only consider the True Wind, as the particle's movement is relative to Earth's surface.
Sofina
Homework Statement
A ship is moving South (S) with Ship Velocity S.V = 15m/s . The apparent wind is southwest (SW) with velocity A.W.=26m/s. This goes on for one hour and after, the ships turns (assume instantly) direction to Northeast (NE) and goes on for half an hour.
a)There is a wind particle that at time t=0s is where the ships at this time. How much distance has the particle traveled after 1 and a half hour?
b) How much is the True Wind and in which direction?
c)How much is the Apparent Wind after the ship turned?
Relevant Equations
None
Hello everyone.
Sorry for the mistakes on my English on this post and on the H/W statements (it is translated by me).
I have a homework problem on Meterology Physics, about a ship's Apparent Wind , and it is about the a) question and maybe i don't know well the theory to solve this problem.
(I have solved the b) & c) question)

So.. I have a solution in my mind but I am not sure if it is right.
For my solution I assume that, at the time t=0s , the particle interacts both with the Ship Wind and the True Wind, so it moves with the Apparent Wind velocity for some seconds. (And after I assume that the True Wind interacts again, so the final velocity of the particle is the velocity sum of Apparent Wind velocity and True Wind Velocity.)

Is it right to assume that the ship wind interacts with the particle?
Or is it only the True Wind that interacts with it?

Sofina said:
the particle interacts both with the Ship Wind and the True Wind
That is such an odd view that I wonder whether you understand what these terms mean.
It is just about frames of reference. True Wind is the movement of the air relative to Earth's surface; apparent wind is the air's movement relative to the ship.
When it asks how far a particle of air moves in a given time, that is relative to the Earth. The particle doesn't care what the ship is doing.

haruspex said:
That is such an odd view that I wonder whether you understand what these terms mean.
It is just about frames of reference. True Wind is the movement of the air relative to Earth's surface; apparent wind is the air's movement relative to the ship.
When it asks how far a particle of air moves in a given time, that is relative to the Earth. The particle doesn't care what the ship is doing.

yes, I think I haven't understood how the ship wind works.
Can the ship wind, the wind that is made of any moving thing, affects its surroundings? (yes?)

My point of view (that I, also, thought was odd) is that the particle is affected both by the Ship Wind and by the True wind at this moment (t=0s), so the outcome is the velocity vector sum of these two.

The professor told us that almost none solved this problem last year, so I tried to think something more complicated.
The other solution that I thought is that the particle is only affected by the true wind so it goes with it's velocity, but I thought (maybe) it was too simple thinking?

Sofina said:
I haven't understood how the ship wind works.
By ship wind I assume you mean apparent wind.
Suppose there is no wind. If you cycle at S 20km/h you will feel a wind of 20km/h on your face, because that is the relative velocity you have to the air. This is the apparent wind to you.
If there is actually a crosswind from the E you will feel an apparent wind from some angle towards SE.
Sofina said:
the particle is affected both by the Ship Wind and by the True wind
Ship wind and true wind are just two views of the same thing. Which the particle is affected by depends on your view, but in no view is it affected by both.

To make it easy, suppose the ship is going E at 10km/h and the true wind is from the S at 10km/h.
To an observer on the ship the particle is affected by ship wind, 14km/h from the SE. After one hour the particle is 10km N of the observer because of the true wind and 10km W because of the ship's movement, making it 14km NW, as expected based on ship wind.
To an observer on the shore, there is only the true wind. The ship is irrelevant. After one hour the particle is 10km N.
Sofina said:
The other solution that I thought is that the particle is only affected by the true wind so it goes with it's velocity
Although it doesn't specifically say so, question a is asking how far the particle has moved relative to Earth's surface. So yes, just use true wind.

Sofina

## 1. What is the apparent wind problem in meteorology physics?

The apparent wind problem is a phenomenon in meteorology physics where the direction and speed of the wind that is felt by an observer differs from the actual direction and speed of the wind. This is due to the motion of the observer, such as a moving boat or airplane, which creates an apparent wind that is a combination of the true wind and the observer's motion.

## 2. How is the apparent wind problem calculated?

The apparent wind problem is calculated using vector addition. The true wind vector, which represents the actual direction and speed of the wind, is added to the observer's velocity vector. The resulting vector is the apparent wind, which is the wind that the observer experiences.

## 3. What factors can affect the apparent wind problem?

There are several factors that can affect the apparent wind problem, including the speed and direction of the true wind, the speed and direction of the observer's motion, and the angle at which the true wind and observer's motion intersect. The shape and size of the observer's body can also impact the apparent wind.

## 4. How does the apparent wind problem impact sailing and aviation?

The apparent wind problem is crucial for sailors and pilots to understand, as it affects their ability to navigate and control their vessels. In sailing, the apparent wind determines the optimal angle and trim of the sails, while in aviation, it affects the performance and handling of the aircraft. Understanding the apparent wind problem is essential for safe and efficient navigation in both sailing and aviation.

## 5. Are there any methods to mitigate the effects of the apparent wind problem?

There are various methods that can be used to minimize the impact of the apparent wind problem. In sailing, techniques such as tacking and gybing can be used to adjust the angle of the vessel in relation to the true wind. In aviation, pilots can adjust the aircraft's speed and direction to compensate for the apparent wind. Additionally, advanced technologies, such as airfoils and winglets, have been developed to reduce the effects of the apparent wind on aircraft performance.

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