Weather and Climate Flashcards
Rain
Liquid water in the form of droplets that have condensed from atmospheric water vapour and then become heavy enough to fall under gravity.
A major component of the water cycle and is responsible for depositing most of the fresh water on the Earth.
Types of Rainfall
Convectional Rainfall
Relief Rainfall
Frontal Rainfall
Convectional Rainfall
Occurs when the energy of the sun heats the surface of
the Earth, causing water to evaporate to form water vapour.
When the land heats up, it warms the air above it.
This causes the air to expand and rise. As the air rises, it cools and condenses.
This process of condensation forms clouds high in the atmosphere.
If this process continues, rainfall will occur.
This type of rainfall is widespread in tropical areas (between the Tropic of Cancer and Tropic of Capricorn)
Relief Rainfall
Occurs when warm moist air from the Atlantic Ocean rises up over mountains.
When the warm air rises, it cools and condenses to form clouds, which bringrain.
Once the air has passed over the mountains, it descends and warms.
This creates drier conditions known as arainshadow.
Frontal Rainfall
Occurs when a warmfrontmeets a coldfront. The heavier cold air sinks to the ground and the warm air rises above it.
When the warm air rises, it cools.
The cooler air condenses and form clouds. The clouds bring heavyrain.
How Clouds are Formed
Formed when water vapor, an invisible gas, turns into liquid water droplets.
These water droplets form on tiny particles, like dust, that are floating in the air.
You hang up a wet towel and, when you come back, it’s dry.
Importance of Clouds
Without clouds, average surface temperatureswouldrise by as much as 22 degrees Celsius
This extreme temperature spikewould notonly destroy the habitats of most flora and fauna
Killing off whatever survived the drought
Itwouldalso melt the polar ice caps
Cause massive flooding of coastal cities
Warms and cools the planet
Clouds cool the Earth’s surface by reflecting incoming sunlight.
Clouds warm the Earth’s surface by absorbing heat emitted from the surface and re-radiating it back down toward the surface.
Clouds warm and dry the Earth’s atmosphere and supply water to the surface by forming precipitation.
Humidity
Humidity is the concentration of water vapor present in the air.
Water vapor, the gaseous state of
water, is generally invisible to the human eye.
Humidity indicates the likelihood for precipitation, dew,
or fog to be present.
Humidity depends on the temperature and pressure of the system of interest.
Types of Humidity
Absolute Humidity
Relative Humidity
Absolute Humidity
Measures the amount of water in the air.
Relative Humidity
Compares this with what the air can hold at a given temperature.
Complete dry air has a relative humidity of 0% water vapors.
Saturated air has a capacity of 100%
