Lecture 5 Flashcards
Describe the Coriolis effect
- this effect changes the intended path of a moving body
- > causes objects moving on the Earth to follow curved paths
-it acts on all moving objects but most pronounced on objects travelling long distances
Why is the Coriolis effect generated
- it is generated because of the Earth’s rotation to the East
- > at an effectively constant anglular velocity
- also, different latitudes have different linear speeds
- > thus, the difference in the speed of Earth’s rotation at different latitudes causes the Coriolis effect
- moving away from the equator=pushing ahead
- moving towards the equator=falling behind
Describe the Coriolis effect in respects to the Northern and Southern Hemisphere
Northern Hemisphere
->an object will follow a path to the right of its intended direction
Southern Hemisphere
->an object will follow a path to the left of its intended direction
Is the distance that a point on Earth has to travel in a day shorter with increasing latitude
- yes
- > a location near the pole travels in a circle not nearly as far in a day as will an area at the equator
- > therefore,t heir velocities must not be the same
What happens to the velocity of the Earth as the latitudes increases
- as the latitude increases, the Earth’s velocity regarding its rotation on its axis decreases
- > this change in velocity is the true cause of the Coriolis effect
Where is the maximum Coriolis effect and where is there no Coriolis effect
- there is maximum Coriolis effect at the poles
- >there is no Coriolis effect at the equator
What is the acceleration for air moving northwards/southwards in the northern hemisphere and air moving northwards/southwards in the southern hemisphere
Northern hemisphere
- > for air travelling northwards, there is an eastward acceleration
- > for air travelling southwards, there is a westward acceleration
Southern hemisphere
- > for air travelling northwards, there is a westward acceleration
- > for air travelling southwards, there is an eastward acceleration
Contrast zonal to meridional direction of air movement
Zonal movement
- > this means the air is moving in the east-west direction
- > if it is moving eastward, it would take less time to complete one entire rotation as it is travelling faster than the Earth’s surface
- > if it is moving westward, it is taking more time to complete one entire rotation, as it is opposing the Earth’s rotation
Meridional movement
->this means the air is moving in the north-south direction
Describe the change in angular velocity for air as it goes East in the Northern Hemisphere
- there is an increase in angular velocity
- .as there is movement away from the axis of rotation, which is the pole
- > this movement away from the pole results in a movement towards the equator
- note eastward acceleration in the Northern Hemisphere means a southward acceleration
- > for westward motion in the northern hemisphere, there would be northward acceleration
-all of this is the opposite for southern hemisphere motions
Describe the Hadley cell
- between the equator and 30 degrees north/south of the equator
- > warm, moist air rises at the Equator
- > flows poleward and is deflected to the east
- > sinks in subtropics and returns as surface flow(deflected to the west)
- drives northeasterly trades in the sub-tropics
- drives northeasterly trades in sub-tropics
Describe the Ferrel cell
- operates at mid-latitudes
- poleward surface flow, rising in mid-latitudes
- > returns equator ward at height and sinks in subtropics
-drives westerlies in mid-latitudes
Describe the Polar cell
- the air has grown cold over the poles and is blowing towards the equator at the surface
- > turning west
- between 50 and 60 degrees latitude, this air has taken up enough heat and moisture to ascend
- > but the polar air is cooler and denser than air in the Ferrel cell
- > therefore, there is no mixing
- > it creates an unstable zone between the Ferrel and Polar Cell
-therefore, at high altitude the ascending air from 50 degrees and 60 degrees turns poleward, completing the circuit
How are subtropical highs created
-descending air at 30 degrees north and south latitudes creates high-pressure zones called subtropical highs
How are polar highs created
-descending air at the poles creates high-pressure regions called polar highs
What does high pressure mean for precipitation
-high pressure= dry and clear conditions
- low pressure= cloudy conditions, lots of precipitation
- > since rising air cools and can’t hold its water vapor
