Wx Theory Part 1

What is the primary cause of weather (wx)?

Uneven heating and cooling of the Earth’s surface.

What are the main components of the atmosphere by percentage?

78% Nitrogen, 21% Oxygen, 1% other gases.

What is the range of water vapor in the atmosphere?

Varies from 0% to 4% by volume.

Name the layers of the atmosphere from bottom to top.

Troposphere, Tropopause, Stratosphere, Mesosphere, Thermosphere.

What is the altitude range of the Troposphere over the poles and equator?

Up to 20,000 feet over the poles

up to 56,000 feet over the equator.

Where does the majority of weather phenomena occur?

In the Troposphere.

What is the temperature lapse rate in the Troposphere?

Decreases approximately 2°C per 1,000 feet gained.

jet streams and clear air turbulence are located most commonly where?

in the tropopause

stratosphere altitude is

from the tropopause to ~160,000’

where does very little wx/turbulence occur? can clouds be here?

stratosphere

yes, some types of clouds extend into it. Ice clouds can be here

How is temperature in the troposphere vs tropopause vs strasophere?

troposphere: temp lapse rate (decreases as alt increases)

tropopause: abrupt change

stratosphere: increases w/ altitude increase

What is atmospheric pressure?

The weight of all the air molecules above you.

At sea level, what is the standard atmospheric pressure and temp?

29.92 in-Hg

15°C

what is convection

• As warm air rises it eventually cools off, sinks, and warms up, rises, etc

• results from uneven heating of air by contrasting surface temps

pressure gradient forces

The force created by pressure differences that drive the wind

moves from high to low pressure perpendicular to isobars

what are isobars and how do we read pressure gradients?

isobars connect area of equal pressure

if they are closer together = faster pressure changes = stronger wind/wx

How does the Coriolis force affect air movement in the northern and southern hemispheres?

In the northern hemisphere, air deflects to the right

In the southern hemisphere, air deflects to the left.

how does pressure gradience force, Coriolis force, and wind move along isobars w/o surface friction?

PGF - high to low and perpendicular

Coriolis - opposite of PGF

wind - 90* to the right of both

What is the role of friction in wind movement?

Friction slows wind down and allows deflection across isobars towards lower pressure.

how does pressure gradience force, Coriolis force, and wind move along isobars w/ surface friction?

PGF - does not change, high to low and perpendicular

coriolis - reduced and deflected

results in wind - reduces and deflected towards lower pressure

What is the pressure lapse rate in the troposphere?

Decreases approximately 1 inch of mercury per 1,000 feet of altitude gained.