The Atmosphere in motion Flashcards
give the five main weather variables
temperature air pressure humidity cloudiness wind speed and direction
does wind contain lots or little of energy
a huge amount
from which pressure gradient to which does wind flow
high to low pressure
what determines the speed of wind
pressure differential
av speeds for winds
10-30 km per hour
why do windier days feel colder
the thickness of boundary around your skin is reduced
what three factors control the speed and direction of the wind
pressure-gradient force
coriolis force
friction
how does pressure-gradient impact wind speed
winds flow more slowly over spaced out isobars (low pressure gradient) and more quickly over close isobars (high pressure gradient)
how does the coriolis effect affect the wind
in the NH, pulls wind to the right as it flows towards low pressure.
coriolis+ pressure combined= wind is parallel to isobars (geostrophic winds)
higher speed= more affected by coriolis
impact of friction on wind
winds move more slowly near the ground, can reduce coriolis effect by slowing down wind, ensures that not all winds are geostrophic
what causes atmospheric circulation overall
uneven heating from the sun
what is the intertropical convergence zone
low pressure region of the tropics at a zone of convergence
what direction do anticyclones flow in the nh
clockwise
what direction do cyclones flow in the nh
anticlockwise
explain weather conditions at high pressure
winds converge at top and diverge at bottom.
cold dense air is drawn downwards (sinks), where it is compressed and heated adiabatically, good weather
explain weather conditions at low pressure
winds converge at bottom and diverge at top.
warm, moist air rises and cools, condensing and forming clouds, precipitation
describe the Hadley cells
blocks of 30 degrees.
high level winds are westerlies and low level ones are trade winds returning to the tropics, nearly easterlies due to friction
what is the polar front jet stream
high speed westerly geostrophic wind that occurs at top of troposphere over the polar front due to a steep pressure gradient
what causes jet streams
unique air masses converging at the boundaries between cells
why is the tropopause lower at the poles
higher pressure and distant from the heat of the equator
what prevents jet streams from being straight?
rossby waves
what is monsoon circulation
a seasonally reversing wind system
explain monsoon circulation in winter
cold high pressure over central and northern asia contrasts with warm waters around India. and the low pressure equator. creates dry winds across india (blowing from land-> sea)
explain monsoon circulation in summer
low pressure over south asia (India), higher pressure in Indian Ocean causes water-laden winds to flow across india.
what is the name of the circulation system caused by a pressure gradient force, how does it work
Walker circulation.
east trade winds push warm water to the west, causing it to “pile up”
this causes cold water to upwell on the east to replace it
heated, low pressure air in the west causes more unsettled weather
temp of the sea reinforces the easterly winds
what is El Niño
weakened trade winds mean less warm water on the west, and less upwelling on the east
Changes the wind patterns so the low pressure is over the middle of the ocean and flows west and east
Can increase global temperatures
what is la niña
strengthening of trade winds, more upwelling in the east and warm, low pressure moves further west, over indonesia.
impacts of el nino
drought conditions in the west, increase global temperatures and wind patterns, impact on monsoons in asia, decline in fish population due to fewer nutrients upwelling
what is southern oscillation
link between the el nino events and changing pressure over the equator
what are katabatic winds
a wind that carries high density air down a slope under the force of gravity
using which scale are hurricanes classified
saffir-simpson hurricane wind scale
what is a hurricane
a very strong cyclone
what are hurricanes over the pacific called
typhoons
what are hurricanes over the indian ocean called
tropical cyclones
what causes a thunderstorm
updraft of warm humid air releases latent heat very quickly.
name four types of deserts
polar deserts, coastal deserts, subtropical deserts, rainshadow deserts
what is a desert
a barren area of landscape where little precipitation occurs, and living conditions are hostile for plant and animal life
less than 25 cm of rainfall a year
