This document discusses precipitation, the hydrosphere, and the hydrologic cycle. It defines precipitation as water released from clouds in various forms such as rain, snow, or hail. It is an important part of the water cycle as it delivers atmospheric water to the Earth. The hydrosphere is defined as all the water on a planet, including surface water, groundwater, and atmospheric water vapor. The hydrologic cycle describes how water moves through the hydrosphere, evaporating from oceans into the atmosphere, condensing into clouds, falling as precipitation, collecting in rivers and lakes, and eventually returning to the oceans to restart the cycle.
2. Precipitation
Precipitation is water released from clouds
in the form of rain, freezing rain, sleet, snow,
or hail. It is the primary connection in the
water cycle that provides for the delivery of
atmospheric water to the Earth. Most
precipitation falls as rain.
3. Precipitation
O Water vapour, droplets of water suspended in the air, builds
up in the Earth's atmosphere. Water vapour in the
atmosphere is visible as clouds and fog. Water vapour
collects with other materials, such as dust, in clouds.
O Precipitation condenses, or forms, around these tiny pieces
of material, called cloud condensation nuclei (CCN).
5. Precipitation
Precipitation is part of the water cycle.
Precipitation falls to the ground as snow and
rain. It eventually evaporates and rises back into
the atmosphere as a gas. In clouds, it turns
back into liquid or solid water, and it falls to
Earth again. People rely on precipitation for
fresh water to drink, bathe, and irrigate crops for
food.
6. Rain
O Rain is precipitation that falls to the surface of the Earth as water
droplets. Raindrops form around microscopic cloud condensation
nuclei, such as a particle of dust or a molecule of pollution.
O Rain that falls from clouds but freezes before it reaches the ground
is called sleet or ice pellets.
O Even though cartoon pictures of raindrops look like tears, real
raindrops are actually spherical.
7.
8. Hail
O Hail forms in cold storm clouds. It forms when
very cold water droplets freeze, or turn solid,
as soon as they touch things like dust or dirt.
The storm blows the hailstones into the upper
part of the cloud. More frozen water droplets
are added to the hailstone before it falls.
9. Hail
Unlike sleet, which is liquid when it forms
and freezes as it falls to Earth, hail falls as a
stone of solid ice.
Hailstones are usually the size of small
rocks, but they can get as large as 15
centimetres (6 inches) across and weigh
more than a pound.
10.
11. Snow
O Snow is precipitation that falls in the form of ice crystals.
Hail is also ice, but hailstones are just collections of frozen
water droplets. Snow has a complex structure. The ice
crystals are formed individually in clouds, but when they fall,
they stick together in clusters of snowflakes.
O Snowfall happens when many individual snowflakes fall
from the clouds. Unlike a hail storm, snowfall is usually
calm. Hailstones are hard, while snowflakes are soft.
12. Snow
O Snowflakes develop different patterns, depending
on the temperature and humidity of the air.
O When snow falls in the form of a ball instead of soft
flakes, it is called graupel. This happens when
snow is melted and precipitation forms around the
snow crystal.
13. Snow
O Snow requires temperatures at the ground
to be near or below freezing—less than 0
degrees Celsius (32-degrees Fahrenheit).
Snow that falls on warmer ground melts
on contact.
14. Precipitation
Global warming also causes changes in
global precipitation. When the planet is
hotter, more ice evaporates in the
atmosphere. That eventually leads to more
rainy precipitation. It usually means wetter
weather in parts of North America, for
example, and drier conditions in tropical
areas that are usually humid.
15. Hydrosphere
O A hydrosphere is the total amount of water
on a planet. The hydrosphere includes
water that is on the surface of the planet,
underground, and in the air.
16. Hydrosphere
O On Earth, liquid water exists on the surface in the
form of oceans, lakes and rivers. It also exists
below ground—as groundwater, in wells and
aquifers. Water vapour is most visible as clouds
and fog.
O The frozen part of Earth's hydrosphere is made of
ice: glaciers, ice caps and icebergs.
17. Hydrosphere
Water moves through the hydrosphere in a
cycle. Water collects in clouds, then falls to
Earth in the form of rain or snow. This water
collects in rivers, lakes and oceans. Then it
evaporates into the atmosphere to start the
cycle all over again. This is called the water
cycle or the hydrologic cycle.
20. Hydrologic Cycle
O The hydrologic cycle begins with the evaporation of
water from the surface of the ocean. As moist air is
lifted, it cools and water vapour condenses to form
clouds. Moisture is transported around the globe until
it returns to the surface as precipitation. Once the
water reaches the ground, one of two processes may
occur; 1) some of the water may evaporate back into
the atmosphere or 2) the water may penetrate the
surface and become groundwater.
21. Hydrologic Cycle
Groundwater either seeps its way to into the
oceans, rivers, and streams, or is released back
into the atmosphere through transpiration. The
balance of water that remains on the earth's
surface is runoff, which empties into lakes, rivers
and streams and is carried back to the oceans,
where the cycle begins again.
23. Past Papers
A. Draw and label a diagram of the
Hydrologic Cycle. (10mks.)
B. Discuss the following terms: Evaporation
and Precipitation (5mks.)
24. Past Papers
5 (a) Draw a annotated diagram of the hydrological
cycle, include the following: (5 marks)
O Evaporation
O Condensation
O Precipitation
O Transpiration
O Infiltration
O Percolation
O Surface flow
O Channel flow
O The water table
