Earth Science Ch. 18
Hygrometer
An instrument that measures relative humidity
Precipitation
Any form of water that falls from a cloud
Which of the following processes can produce either rain or snow?
Bergeron Process
Which type of cloud is high, white, and thin?
Cirrus
Describe the difference between clouds and water vapor
Clouds are a form of condensation: visible mixtures of tiny droplets of water or tiny crystals of ice. Water Vapor is the gas phase of water.
Stratus
Clouds are best described as sheets or layers that cover much or all of the sky
How are clouds classified?
Clouds are classified on the basis of their form and height
Cumulus
Clouds consist of rounded individual cloud masses
Cirrus
Clouds that are high, white, and thin
List two changes of state for water that cause latent heat to be released
Condensation and Freezing
Compare and contrast clouds and fogs
Fog is defined as a cloud with its base at or very near the ground. Physically there is no difference. Difference is the method and place of formation.
What must happen in order for precipitation to form?
For precipitation to form cloud droplets must grow in volume by roughly one million times
Latent Heat
Heat used to melt ice (Latent means hidden). Stored in liquid until water returns to solid form
If the water-vapor content of air remains constant, lowering air temperature causes a(n)
Increase in relative humidity
What word is used to describe a cloud as rainy?
Nimbus
Rain, snow, sleet, and hail are all examples of
Precipitation
The ratio of air's water-vapor content to its capacity to hold water vapor at that same temperature is the
Relative Humidity
What does relative humidity describe about air?
Relative humidity is a ratio of the air's actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure
A low cloud that blankets the sky and often generates precipitation is called a(n)
Stratus Cloud
Humidity
The amount of water vapor in the air
Write a general statement relating air temperature and the amount of water vapor needed to saturate the air
The amount of water vapor required for saturation depends on the temperature of the air
Condensation
The change from a gas to a liquid
Evaporation
The change of a liquid to a gas
As you drink an ice-cold beverage on a hot day, the outside of the glass becomes wet. Explain why this happens
The cold glass cools the air in contact with it below the air's dew point and water vapor condenses on the glass.
What happens to heat during a change of state?
The process of changing state requires that energy is transferred in the form of heat.
Describe how the temperature profile of air near Earth's surface controls the type of precipitation that falls to the ground
The type of precipitation that reaches Earth's surface depends on the temperature profile in the lowest few kilometers of the atmosphere. Temperature profile is the way the air temperature changes with altitude. For example, even on a hot summer day, rainfall may have begun as a snowstorm high in the clouds overhead.
Supersaturated
When air is saturated (100% relative humidity) with respect to water
How does the temperature of air influence its ability to hold water?
When saturated, warm air contains more water vapor than cold air
List two ways that relative humidity can be changed
When water-vapor content of air remains constant, lowering air temperature causes an increase in relative humidity, and raising air temperature causes a decrease in relative humidity
Sublimation
a change directly from the solid to the gas state without becoming liquid
Bergeron Process
a process that produces percipitation; the process involves tiny ice crystals in a supercooled cloud growing larger at the expense of the surrounding liquid droplets
Relative Humidity
a ratio of the air's actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure
Saturated Air
air that contains as much water vapor as is possible for that temperature
What is the difference between condensation and precipitation?
condensation is the transformation of state from a gas to a liquid and precipitation is next stage after condensation where water droplets become larger and larger so as they fall under gravity in form of rain from the cloud
collision-coalescence process
formation of precipitation, where tiny droplets accumulate, fall, and collide with other small droplets until rain drops form and fall.
Dew Point
the temperature at which the water vapor in the air becomes saturated and condensation begins
What is the most important gas for understanding atmospheric pressure?
water vapor
