WATER IN THE ATMOSPHERE
During a rainstorm, the air feels moist On a clear, cloudless day, the air may feel dry As the sun heats the land and oceans, the amount of water in the atmosphere changes Water is always moving between the atmosphere and Earth s surface
The Water Cycle The movement of water between the atmosphere and Earth s surface is called the water cycle Evaporation is the process by which water molecules in liquid water escape into the air as water vapor As part of the water cycle, some of the water vapor in the atmosphere condenses to form clouds Water cycle song
Humidity Humidity is the measure of the amount of water vapor in the air Air s ability to hold water vapor depends on its temperature Warm air can hold more water than cold air
Relative Humidity Weather reports usually refer to the water vapor in the air as relative humidity 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 5 gallon bucket example
How clouds form When you look at a cloud you are seeing millions of tiny water droplets or ice crystals Clouds form 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 Role of Cooling Cold air holds less water vapor than warm air As air cools, the amount of water vapor it can hold decreases The water vapor condenses into tiny droplets of water or ice crystals The temperature at which condensation begins is called the dew point If the dew point is above freezing, the water vapor forms droplets If the dew point is below freezing, the vapor turns into ice crystals
Dew Point minilab Fill a beaker with cool tap water record the temperature Add ice cubes to the beaker and stir When moisture condenses on the outside of the beaker, record the temperature of the water again This is the exact dew point of Ms. Parrish s classroom
Questions Would the dew point be the same if you performed this experiment on different days? Probably not; the dew point depends on the temperature and relative humidity, which change from day to day Explain why dew forms on the plants in the early morning. Dew forms when the ground reaches the temperature at which water vapor condenses
The role of particles Salt crystals, dust from soil and smoke are all tiny particles that water vapor condenses to These are needed for water to actually condense (it needs something to hold on to)
The most abundant gas in the atmosphere is A. ozone B. water vapor C. nitrogen D. oxygen
Air pressure is typically measured with a A. thermometer B. satellite C. hot air balloon D. barometer
The layers of the atmosphere are classified according to changes in A. altitude B. temperature C. air pressure D. pollutants
True or False Weather is the condition of Earth s atmosphere at a particular time and place TRUE
True or False The force pushing on an area or surface is called density FALSE
True or False Earth s weather occurs in the Thermosphere FALSE
True or False The ozone layer is found in the exosphere FALSE
What two gases make up approximately 99% of Earth s atmosphere? a. Nitrogen and carbon dioxide b. Oxygen and carbon dioxide c. Nitrogen and hydrogen d. Nitrogen and oxygen
In the troposphere, as altitude increases a. Air pressure decreases b. Temperature decreases c. Air density decreases d. All of the above e. None of the above
The ozone layer is found in the a. Troposphere b. Stratosphere c. Mesosphere d. Thermosphere
Energy from the sun travel to Earth s surface from a. Radiation b. Convection c. Conduction d. Evaporation
Rising warm air transports thermal energy by a. Conduction b. Convection c. Radiation d. Condensation
Bands of high altitude, high speed winds are called a. Jet streams b. Sea breezes c. Land breezes d. Local winds
True or False The transfer of heat by the movement of fluid is called conduction FALSE
True or False Winds that blow steadily from specific directions for long distances are called sea breezes FALSE
When the temperature reaches the dew point, the relative humidity is a. Zero b. About 10% c. About 50% d. 100%