Science, Chapter 2, Section 4:Water in the Atmosphere Flashcards
What is humidity
The amount of water vapor in the air
What is relative humidity
Amount of water vapor held by air compared with how much it can hold
What is the dew point
When air is fully saturated with water vapor and condensation occurs
What is evaporation
when water changes from a liquid to a gas.
What is condensation
when water changes from a gas to a liquid
How is air similar to a sponge?
They can both hold and release water.
Define evaporation
the process by which water molecules in liquid water escape into the air as water vapor
Describe the water cycle
precipitation is rain from clouds
rain goes into lakes, oceans, streams as run-off
water evaporates from plants into the sky
water that evaporates condenses into clouds
Define humidity
a measure of the amount of water vapor in the air
Define relative humidity
The percentage of water vapor in the air compared to the maximum amount the air can hold
How do you measure relative humidity
with a psychrometer
describe a psychormeter
it has 2 thermometers, a wet bulb thermometer and a dry bulb thermometer
how do clouds form
They form when water vapor in the air becomes liquid or ice crystals
Define condensation
the process by which molecules of water vapor in the air become liquid
How does water condense
cold air holds less water vapor than warm air. So, as air cools, the amount of water vapor it can hold decreases
Define dew point
the temperature at which condensation begins
What happens if the dew point is below freezing
water vapor may change directly into ice crystals
What is dew
water that condenses from air onto a cold surface
why are the tops of some mountains always covered by clouds
moist air moving up into the air is getting cold because it is less dense and rises with the convection current and forms clouds
What happens when water vapor condense out of the air?
It rains
What happens as the sun rises and warms the air above a lake
the water droplets evaporate
How does a psychrometer work?
The wet bulb thermometer has a cloth covering that is moistened with water. Air is blown over both thermometers. Because the wet bulb thermometer is cooled by evaporation, its reading will drop below the dry bulb thermometer
What conditions are needed for clouds to form
cold air, so the water vapor in the air can become liquid water or ice crystals
How are condensation and humidity related
Once the air can hold no more water (the humidity) , it will start to condense (or form water) in the form of rain or clouds
