Weather Factors

1
Weather Factors

• Chapter 16

2
What does the movement of heat in the atmosphere
cause?
3
The movement of heat in the atmosphere causes
temperatures to change, rain to fall, and winds
to blow.
4
Energy from the Sun

• Most of the energy from the sun travels to Earth
  in the form of visible light and infrared
  radiation. A small amount arrives as ultraviolet
  radiation.

5
Energy in the Atmosphere

• Some sunlight is absorbed or reflected by the
  atmosphere before it can reach the surface. The
  rest passes through the atmosphere to the
  surface.
• Absorbed
• Water vapor and other gases absorb infrared
  radiation.
• Ozone layer absorbs ultraviolet rays.
• Clouds, dust, and other gases also absorb energy.
• Reflected
• Dust particles and gases in the atmosphere
  reflect light in all directions, a process called
  scattering.

6
Energy at Earths Surface

• When Earths surface is heated, it radiates most
  of the energy back into the atmosphere as
  infrared radiation.
• The process by which gases hold heat in the air
  is called the greenhouse effect.

7
How are thermal energy and temperature related?
8

• Thermal energy and temperature are related
  because temperature is the average amount of
  energy of motion of each particle of a substance
  whereas thermal energy is the total energy in a
  substance.

9
How Heat is Transferred

• Heat is transferred through
• Radiation
• Conduction the direct transfer of heat from one
  substance to another substance that it is
  touching.
• Convection the transfer of heat by the movement
  of a fluid.
• Radiation, conduction, and convection all work
  together to heat the troposphere.

10
Winds
11
What is Wind?

• A wind is the horizontal movement of air form an
  area of high pressure to an area of lower
  pressure.
• Winds are caused by differences in air pressure.
• Winds are measured using an anemometer.
• WindChill factor is the increased cooling a wind
  can cause.

12
Local Winds

• Local winds are winds that blow over short
  distances.
• Local winds are caused by the unequal heating of
  Earths surface within a small area.
• A sea breeze or a lake breeze is a local wind
  that blows from an ocean or lake.
• A land breeze is a flow of air from land to a
  body of water.

13
Global Winds

• Global winds are winds that blow steadily from
  specific directions over long distances.
• Global Convection Currents
• The Coriolis Effect

14
Global Wind Belts

• The major global wind belts are the trade winds,
  the polar easterlies, and the prevailing
  westerlies.
• Doldrums
• Horse latitudes
• Trade winds
• Prevailing westerlies
• Polar easterlies
• Jet Streams

15
Water in the Atmosphere
16
Humidity

• Humidity is the measure of the amount of water
  vapor in the air.
• Relative humidity is the percentage of water
  vapor that is actually in the air compared to the
  maximum amount of water vapor the air can hold at
  a particular temperature.
• Relative humidity can be measured with an
  instrument called a psychrometer.

17
How Clouds Form

• Clouds from when water vapor in the air condenses
  to form liquid water or ice crystals.
• Molecules of water vapor in the air become liquid
  water in the process of condensation.
• The temperature at which condensation begins is
  called the dew point.

18
Types of Clouds

• Scientists classify clouds into three main types
  based on their shape
• Cirrus Clouds wispy, feathery clouds
• Cumulus Clouds fluffy, founded piles of cotton.
• Stratus Clouds clouds that form in flat layers
• Autocumulus and autostratus refer to high clouds.
• Clouds that form near the ground are called fog.

19
Precipitation
20
Types of Precipitation

• Rain
• Sleet
• Freezing Rain
• Snow
• Hail
• Modifying Precipitation
• Droughts are long periods of unusually low
  precipitation.
• Cloud seeding is one method used to modify
  precipitation.

21
Measuring Precipitation

• Scientists measure precipitation with various
  instruments including rain gauges and measuring
  sticks.