Transcript Day 28

Day 28
Investigation 6 part 2
Evaporation and Humidity
Vocabulary
• Water vapor is the gaseous phase of water
• Evaporation is when liquid water changes from a
liquid to gas (water vapor)
• Humidity is water vapor in the air
• When it is humid = a lot of water vapor in the air
Saturated
• When air contains as much water vapor as it can
Only a little bit of water vapor to
saturate cold air
Takes a lot of water vapor to saturate
warm air
Relative Humidity
• How meteorologist often describe the amount
of water vapor in the air
• Measured in percentages
• Compares the amount of water vapor in the
air to the amount needed to saturate the air
Relative Humidity = 100%
Would things dry
up very fast?
The air is saturated with
water vapor
Air can absorb any more
water
No evaporation occurs
Into the Air
• Water vapor gets into the air several ways
– Liquid water can evaporate when it absorbs
energy
• Radiation
• Conduction
Transpiration
• Water leaves plants as vapor
• Condensation on the side of a terrarium
Not just plants
• All terrestrial animals exhale water vapor
when they breathe
• Also from:
– Fires
– Internal combustion engines
– Volcanic eruptions
Hygrometer
• Measure relative humidity
• Measures the water vapor in the air and
compares that to the amount needed to
saturate the air
• Relative Humidity as a percent
STUDENT SHEET
• COMPLETE PG. 31 “RELATIVE HUMIDITY” IN
YOUR LAB BOOK.
HOMEWORK
• OPEN TO PAGE 33 “RESPONSE SHEET - WATER
IN THE AIR” IN YOUR LAB BOOK.
• COMPLETE FOR HOMEWORK.