PowerPoint Presentation

1Earth Science Chapter 18.1 Water in the Atmosphere

2Ag Earth Science Chapter 18.118.1 Vocabulary3precipitationAny form of water that falls from a cloud

4latent heatThe energy absorbed or released during a change in state

5evaporationThe process of converting a liquid to a gas

6condensationThe change of state from a gas to a liquid

7sublimationThe conversion of a solid directly to a gas without passing through the liquid stage

8depositionThe process by which water vapor is changed directly to a solid without passing through the liquid state

9humidityA general term referring to water vapor in the air but not to a liquid droplets of fog, cloud, or rain

10saturatedThe state of air that contains the maximum quality of water vapor that it can hold at any given temperature and pressure.

11relative humidityThe ratio of the airs water-vapor content to its water-vapor capacity

12dew pointThe temperature to which air has to be cooled in order to reach saturation

13hygrometerAn instrument designed to measure relative humidity

14

15Water in the AtmosphereWhen it comes to understanding atmospheric processes, water vapor is the most important gas in the atmosphere

Precipitation any form of water that falls from a cloud (rain, sleet, hail, snow, etc..)

16

17Water Changes in StateSolid to Liquid

The process of changing state requires that the energy is transferred in the form of heat

Latent heat hidden heat. The energy absorbed or released during a change in state

18Water Changes in StateLiquid to Gas

Evaporation the process of changing a liquid to a gas

Condensation the process where water vapor changes to a liquid

19Water Changes in StateSolid to a Gas

Sublimation conversion of a solid directly to a gas without passing through the liquid state

Deposition conversion of a vapor directly to a solid

20HumidityHumidity the amount of water vapor in the air

Saturation

Saturated - The state of air that contains the maximum quality of water vapor that it can hold at any given temperature and pressure.

When saturated, warm air contains more water vapor than saturated cold air

21HumidityRelative Humidity

Relative humidity is a ratio of the airs actual water-vapor content compared with the amount of air can hold at that temperature and pressure.

To summarize, when the 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.

22HumidityDew Point

The temperature to which a parcel of air would need to be cooled to reach saturation

23HumidityMeasuring Humidity

Hygrometer - A tool that measures humidity

24

25Ag Earth Science Chapter 18.218.2 Vocabulary26dry adiabatic rateThe rate of adiabatic cooling or warming in unsaturated air

27wet adiabatic rateThe rate of adiabatic temperature change in saturated air

28orographic liftingMountains acting as barriers to the flow of air, forcing the air to ascend

29frontThe boundary between two adjoining air masses having contrasting characteristics

30temperature inversionA layer of limited depth in the atmosphere of limited depth where the temperature increases rather than decreases with height

31condensation nucleiTiny bits of particulate matter that serve as surfaces on which water vapors condenses

32

33Air Compression and ExpansionAdiabatic Temperature Changes

When air is allowed to expand, it cools, and when it is compressed, it warms

34Air Compression and ExpansionExpansion and Cooling

As you travel from earths surface upward through the atmosphere, the atmospheric pressure decreases.

Ascending air = cools and Descending air = warms

35Air Compression and ExpansionExpansion and Cooling

Dry adiabatic rate the rate of cooling or heating of dry air (fast)Wet adiabatic rate The rate of cooling or heating of saturated air (slow)

36Processes That Lift AirFour mechanisms that can cause air to rise are orographic lifting, frontal wedging, convergence, and localized convective lifting.

37Processes That Lift AirOrographic Lifting

Elevated terrains, such as mountains, that act as barriers to air flow (forcing air to ascend)

38Processes That Lift AirFrontal Wedging

Cooler, denser air acts as a barrier over which the warmer, less dense air rises

Front boundary between two different air masses (example cold/warm air masses)

39Processes That Lift AirConvergence

The collision of contrasting air masses that causes the air to rise

40Processes That Lift AirLocalized Convective Lifting

The process that produces rising thermals (localized)

41StabilityStable air tends to remain in its original position, while unstable air tends to rise.

Air stability is determined by measuring the temperature of the atmosphere at various heights.

42StabilityAir is stable when the temperature decreases gradually with increasing altitude

Temperature inversion air temperature actually increases with height

43CondensationCondensation happens when water vapor in the air changes to a liquid (fog, dew, clouds)

For any form of condensation to occur, the air must be saturated

Condensation nuclei - Tiny bits of particulate matter that serve as surfaces on which water vapors condenses

44

45Ag Earth Science Chapter 18.318.3 Vocabulary46cirrus1 of 3 basic cloud forms. Very high clouds that are thin, delicate ice-crystal clouds that have veil-like patches or thin, wispy fibers

47cumulus1 of 3 basic cloud forms. They are billowy individual clouds with flat bases.

48stratus1 of 3 basic cloud forms. They are sheets or layers that cover much or all of the sky.

49Bergeron processA theory that relates the formation of precipitation to supercooled clouds, freezing nuclei, and the different saturation levels of ice and liquid water.

50supercooled waterThe condition of water droplets that remain in the liquid state at temperatures well below 0 degrees.

51supersaturated airThe condition of air that is more highly concentrated than is normally possible under given temperature and pressure conditions. (Greater than 100% humidity)

52collision-coalescence processA theory of raindrop formation in warm clouds (above 0 degrees C) in which large cloud droplets collide and join together with smaller droplets to form a raindrop.

53

54Types of CloudsClouds are classified on the basis of their form and height.

Types of Clouds:

Cirrus (a curl of hair) clouds that are high, white, and thin.

55Types of CloudsCumulus (a pile) clouds that consist of rounded individual cloud masses

56Types of CloudsStratus (a layer) clouds are best described as sheets or layers that cover much or all the sky

57Types of CloudsHigh Clouds

Three types of clouds make up the family of high clouds (cirrus, cirrostratus, and cirrocumulus). They are very high altitude and have ice crystals. Not considered precipitation makers.

58Types of CloudsMiddle Clouds

Middle range clouds (2000-6000 meters). Appear in rounded masses and are larger and denser than higher clouds. Light drizzle or snow may accompany these clouds.

59Types of CloudsLow Clouds

Three members of the family of low clouds (stratus, stratocumulus, nimbostratus). Most common rain clouds as they form a layer across the sky.

60FogFog is defined as a cloud with its base at or very near the ground.

Fogs caused by cooling

When warm, moist air moves over cold areas, the cooling saturates the air below its dew point.

61FogFogs caused by evaporation

When cool air moves over warm water. Evaporation moves into cool air and saturates.

62How Precipitation FormsFor precipitation to form, cloud droplets must grow in volume by roughly one million times.

Cold Cloud Precipitation

Bergeron Process physical processes of supercooling and supersaturation take place.

63How Precipitation FormsWarm Cloud Precipitation

Collision-coalescence process water absorbing particles remove water vapor from the air at relative humidities less than 100 percent forming drops that are quite large. As they move through the cloud, they collide and join together with smaller, slower droplets.

64Forms of PrecipitationThe type of precipitation (rain, snow, sleet, and hail) that reaches the Earths surface depends on the temperature profile in the lowest few kilometers of the atmosphere.

65

66