Development of Geostrophic Winds

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: How Surface Winds Are Created

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 00:00 Introduction to…
  • 00:30 Pressure Gradient Force
  • 2:00 Coriolis Force
  • 3:50 Geostrophic Wind
  • 4:48 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Amy Lange

Amy has taught university-level earth science courses and has a PhD in Geology.

The dominant forces of pressure gradient force and Coriolis force combine to form geostrophic wind flows. In this lesson, we'll examine why many of the winds in the atmosphere actually blow parallel to the prevailing isobars.

Introduction to Geostrophic Wind

There are a number of forces that can either change the force or direction of wind. Two of the biggest forces of wind vectors are the pressure gradient force and the Coriolis force. When these two major forces are combined and are equal to each other we get a type of wind called a geostrophic wind. In this lesson, we'll study how pressure gradient force and Coriolis force are created and the formation of geostrophic winds.

Pressure Gradient Force

One of the largest such drivers is the pressure gradient force. The pressure gradient force is the force that drives air from high to low pressure. Systems in nature are always trying to stay at the lowest energy state possible. High pressure systems are high energy states. If there is a nearby lower pressure area, air will freely move from the high pressure to low pressure area in an attempt to equalize this energy gradient.

You may have been introduced to the idea of isobars, which are imaginary lines of equal pressure. Because the air is wanting to move as quickly and efficiently from high to low pressure it will move the shortest distance between these areas, which is always perpendicular to the isobars. This is described in the following equation for the horizontal portion of the pressure gradient force:

P= inverse -1/p * p

The pressure gradient force, here shown as P, is equal to the inverse of the density times the pressure gradient. The inverse sign is an upside down triangle. The negative (-) at the beginning of the equation designates that we move from high to low across the pressure gradient.

Now, if this was the only force acting on the atmosphere, we could easily predict wind direction. Wind should move from high to low pressure perpendicular to the isobars; however, we observe that higher in the atmosphere, wind is actually moving parallel to the isobars. How can that happen?

Coriolis Effect

We must look at some other forces that act on wind. Another dominant force on wind direction is the Coriolis effect. The Coriolis effect is the diversion of the path of air due to the rotation of the Earth. The Earth is spinning from west to east. The Earth is a sphere, and therefore all points are traveling with the same angular velocity. However, because a point at the equator must travel a much further distance than a point near the pole for full rotation, areas near the pole are actually traveling at a much higher linear velocity.

When an object moves either closer or further from the equator its original momentum is preserved, giving the path a diversion off its original course. Paths in the Northern hemisphere are drug to the right, and paths in the Southern hemisphere are drug to the left. So, if we have wind that is originally blowing according to the pressure gradient force, this wind will be deflected by the Coriolis force. Now, the Coriolis force is not present at the equator, but it increases in intensity the further you approach the poles. The increase in force is due to the greater divergence in linear speed observed at the equator.

Coriolis force is described by this equation:

ƒc = 2 * omega * sin * Phi

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account