Question

Difference between geostrophic winds and jet streams circumpolar whirl

Answer 1

Geostrophic Wind
The velocity and direction of the wind are the net result of the wind generating forces.
The winds in the upper atmosphere, 2 – 3 km above the surface, are free from frictional effect of the surface and are controlled by the pressure gradient and the Coriolis force.
An air parcel initially at rest will move from high pressure to low pressure because of the Pressure Gradient Force (PGF).
However, as that air parcel begins to move, it is deflected by the Coriolis force to the right in the northern hemisphere (to the left in the southern hemisphere).
As the wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force (2 – 3 km above the ground, friction is low and winds travel at greater speeds).
At this point, the wind will be blowing parallel to the isobars (perpendicular to Pressure Gradient Force). When this happens, the wind is referred to as geostrophic wind.
geostrophic wind

Why winds don’t flow from tropical high pressure (in upper troposphere) to polar low (in upper troposphere) directly as shown in figure below?
Because these winds are geostrophic, i.e., they flow at great speeds due to low friction and are subjected to greater Coriolis force.
So they deflect greatly giving rise to three distinct cells called Hadley cell, Ferrel Cell and Polar cell.
Instead of one big cell (as shown in fig) we have three small cells that combinedly produces the same effect.
atmospheric convectional cells

Jet streams
Jet streams are

Circumpolar (situated around or inhabiting around one of the earth’s poles),
narrow, concentrated bands of
meandering,
upper tropospheric,
high velocity,
geostrophic streams,
bounded by low speed winds and
are a part of upper level westerlies.
jet streams formed between boundaries of air masses

Circumpolar
Jet streams are winds that circle around the earth with poles as their centers.
jet stream-Circumpolar

Narrow, concentrated bands
The stream of air is very narrow (50 -150 km across) and, the air in the stream is directed towards the axis of the stream making it very narrow.
Meandering
When the temperature contrast is maximum, jet stream flows in near straight path.
But when temperature contrast reduces, the jet stream starts to follow a meandering path.
So meandering depends on temperature contrast (temperature gradient).
A meander is called peak or ridge if it is towards poles and trough if it is towards equator.


meandering jet streams

Rossby Waves
The meandering jet streams are called Rossby Waves.
Rossby waves are natural phenomenon in the atmosphere and oceans due to rotation of earth.
In planetary atmospheres, they are due to the variation in the Coriolis effect (When temperature contrast is low, speed of jet stream is low, and Coriolis force is weak leading to meandering) with latitude.
Rossby waves are formed when polar air moves toward the Equator while tropical air is moving poleward.
The existence of these waves explains the low-pressure cells (cyclones) and high-pressure cells (anticyclones).
Rossby waves - jet streams

Upper Tropospheric
Jet streams flow just below the Tropopause.
Polar jet streams flow 6 – 9 km above the ground and Sub-tropical jet streams flows 10 – 16 km above the grounds.
jet streams - Upper Tropospheric winds

Why this difference in height?
Recall that troposphere is thicker at equator –– 17 to 18 km, than at poles –– 8 to 9 km.
High velocity
Pressure gradient increases with altitude and creates high velocity winds at higher altitudes.
The friction in the upper troposphere is quite low due to less denser air. Hence the Jet streams flow at great velocities.
Temperature also influences the velocity of the jet stream. The greater the difference in air temperature, the faster the jet stream, which can reach speeds of up to 250 mph (402 kph) or greater, but average about 110 mph (177 kph).


Geostrophic streams
Direction of the jet stream is determined by pressure gradient force (temperature contrast creates pressure gradients) and Coriolis force.
The direction of jet stream is perpendicular to the pressure gradient force.
Bounded by low speed winds
The winds surrounding jet streams are of comparatively low velocities.
Are a part of upper level westerlies
Jet streams are produced due to winds flowing from tropics towards poles (In polar jet streams wind flows from temperate region towards polar region, and in sub-polar jet streams winds flow from sub-tropics towards temperate region).
Anything moving from tropics towards poles deflects towards their right in the northern hemisphere and towards their left in the southern hemisphere due to Coriolis effect. So jet streams flow from west to east in both the hemispheres and hence they are called westerlies or upper level westerlies.

Answer 2

Difference between geostrophic winds and jet streams, circumpolar whirl

Explanation:

• The Geostrophic winds are those winds that are a theoretical winds that are found that are a resultant of the exact balance of the Coriolis force and the pressure gradient force.

• This wind flows direct parallel to the isobars and balance is seldom exact in nature and the flow of the water in the ocean is already a product of the geostrophic current and allows for the divergence to take place and formation of the weather patterns to develop.

• While the jet streams are a fast and narrow meandering system of the air current in the air and are located near the altitude of the tropopause and the westerly winds. The strongest winds are formed at the altitude of the 12 km in the higher altitudes and the weaker are found in the subtropical areas of 10 to 16 km.

• The circumpolar whirl is also called as a polar vortex and is found along with the polar lows a the polar cyclones and are located near the polar surface and have persistent low and cold climates and temperatures.

Know more about the difference between the geostrophic winds and the jet stream and the circumpolar whirl.

• https://brainly.in/question/3607045 answered by Brainly User