Download Chapter 9.3 - Black River Local Schools

Chapter 9: Weather Factors
Section 3: Winds
What is Wind?

Wind – horizontal movement; from high
pressure to lower pressure.
◦ Caused from differences in pressure
 Difference in pressure – caused by unequal heating
of the atmosphere.
Measuring Wind
Winds are described by their direction
and speed.
 Name of wind – Where it comes from

Measuring Wind

Wind speed is measured with an
anemometer.
Wind-Chill Factor

Wind-Chill Factor – the increased cooling
caused by wind.
Local Winds

Local Winds – blow over short distances.
◦ Caused by unequal heating of Earth’s surface
within a small area.
◦ Form only when large scale winds are weak.
Local Winds

Sea Breeze (Lake Breeze) – a local wind
that blows from an ocean or lake.
Local Winds

Land Breeze – flow of air from land to a
body of water.
Global Winds

Global Winds – winds that blow steadily
from specific directions over long
distances.
◦ Created by unequal heating of Earth’s surface
but occur over a large area.
Global Convection Currents

Global Convection Currents –
Temperature differences between the
equator and the poles produce giant
convection currents in the atmosphere.
Global Convection Currents

Coriolis Effect – Earth’s rotation makes
winds curve.
Global Wind Belts
Doldrums – Near Equator; Calm area;
warm air rises; low pressure area
 Horse Latitudes – Calm area; falling air;
high pressure
 Trade Winds – blow from horse latitudes
toward the equator
 Prevailing Winds – blow away from the
horse latitudes toward the poles
