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Identify three properties of the atmosphere and how they interact. Explain why atmospheric properties change with changes in altitude. Section 11.2. Objectives. Properties of the Atmosphere. Review Vocabulary. density: the mass per unit volume of a material. - PowerPoint PPT PresentationTRANSCRIPT
ObjectivesIdentify three properties of the atmosphere and how they interact.
Explain why atmospheric properties change with changes in altitude.
Properties of the AtmosphereSection 11.2
Review Vocabulary
density: the mass per unit volume of a material
Atmospheric properties such as temperature, air pressure, and humidity describe weather conditions.
Properties of the AtmosphereSection 11.2
New Vocabulary
temperature inversion
humidity
saturation
relative humidity
dew point
latent heat
TemperatureParticles have more kinetic energy when they are moving faster, so the higher the temperature of a material, the faster the particles are moving – temperature is a measurement of the speed of the particles.
Heat is the transfer of energy that takes place due to difference in temperature.
Properties of the AtmosphereSection 11.2
Temperature can be measured in degrees Fahrenheit, degrees Celsius, or in kelvin.
Temperature
Properties of the AtmosphereSection 11.2
Measuring temperature
Properties of the AtmosphereSection 11.2
Air Pressure
Air pressure is the pressure exerted on a surface by the weight of the atmosphere above the surface. ( P = Force/area)
The units for pressure are N/m2.
Air pressure is often measured in units of millibars (mb), where 1 mb equals 100 N/m2.
Properties of the AtmosphereSection 11.2
Air Pressure
The density and pressure of the layers of the atmosphere decrease as altitude increases.
The air gets thinner as you go up.
Density of air
Properties of the AtmosphereSection 11.2
Air Pressure
In the atmosphere, the temperature, pressure, and density of air are related to each other.
Pressure-temperature-density relationship
Properties of the AtmosphereSection 11.2
Air Pressure
Temperature, pressure, and density are all related to one another.
If temperature increases, but density is constant, the pressure increases.
If the temperature increases and the pressure is constant, the density decreases.
Pressure-temperature-density relationship
Properties of the AtmosphereSection 11.2
Air Pressure
A temperature inversion is an increase in temperature with height in an atmospheric layer.
Temperature inversion
Properties of the AtmosphereSection 11.2
Air Pressure
On cold clear winter nights, the ground is cold and does not radiate heat to the lower layers of the atmosphere. So the lower layers of air become cooler than the air above them.
Temperature inversion
Properties of the AtmosphereSection 11.2
Air Pressure
A temperature inversion can lead to fog or low-level clouds.
In some cities, a temperature inversion can worsen air-pollution problems.(smog)
Temperature inversion
Properties of the AtmosphereSection 11.2
Air Pressure
The movement of air is commonly known as wind.
In the lower atmosphere, air generally moves from regions of higher density and pressure to regions of lower density and pressure.
Wind
Properties of the AtmosphereSection 11.2
Air Pressure
Near Earth’s surface, wind is constantly slowed by the friction that results from contact with surfaces including trees, buildings and hills.
Higher up from Earth’s surface, air encounters less friction and wind speeds increase.
Wind
Humidity
Humidity is the amount of water vapor in the atmosphere at a given location on Earth’s surface.
Properties of the AtmosphereSection 11.2
Properties of the AtmosphereSection 11.2
Saturation occurs when the amount of water vapor in a volume of air has reached the maximum amount possible for that temperature.
(RH = 100%)
Properties of the AtmosphereSection 11.2
Humidity
The amount of water vapor in a volume of air relative to the amount of water vapor needed for that volume of air to reach saturation is called relative humidity.
RH = water vapor content /water vapor capacity X100%
Relative humidity
Properties of the AtmosphereSection 11.2
Humidity
The dew point is the temperature to which air must be cooled at constant pressure to reach saturation.
(RH = 100%)
Relative humidity
Properties of the AtmosphereSection 11.2
The extra thermal energy contained in water vapor compared to liquid water is called latent heat.
• Change of state diagram.
Properties of the AtmosphereSection 11.2
Humidity
A process in which temperature changes without the addition or removal of thermal energy from a system is called an adiabatic process.
Adiabatic heating occurs when air is compressed, and adiabatic cooling occurs when air expands.
Condensation level
Properties of the AtmosphereSection 11.2
Humidity
Condensation occurs at the lifted condensation level (LCL). Air above the LCL is saturated and thus cools more slowly than air below the LCL.
Condensation level
CH
Atmospheric properties, such as temperature, air pressure, and humidity describe weather conditions.
At the same pressure, warmer air is less dense than cooler air.
Air moves from regions of high pressure to regions of low pressure.
Study Guide Key Concepts
Section 11.2 Properties of the Atmosphere
CH
The dew point of air depends on the amount of water vapor the air contains.
Latent heat is released when water vapor condenses and when water freezes.
Study Guide Key Concepts
Section 11.2 Properties of the Atmosphere
CH
11.2 Section Questions
What is the relative humidity of a parcel of air that has reached its dew point?
a. 25 percent
b. 50 percent
c. 75 percent
d. 100 percent
Atmosphere
CH
a. volume
b. density
c. pressure
d. mass
A sealed container holds only air. If the temperature of the air inside the container is increased, which other property of the air also increases?
11.2 Section Questions
Atmosphere
CH
During which changes of state does water release latent heat?
a. condensing and freezing
b. evaporating and melting
c. evaporating and freezing
d. condensing and melting
11.2 Section Questions
Atmosphere