1.
 Hydrology is the study of water movement and distribution on and below the surface of the Earth,
as well as how human activity affects water conditions and availability. The study of hydrology is
crucial to comprehending the planet's water cycle and how it affects our daily lives, the economy,
and the environment. Water is an essential resource for life and the survival of people, plants, and
animals, which makes hydrology significant. Agriculture, industry, tourism, and the creation of
energy all depend on it.
 Meteorology predicts weather patterns, analyzes the water cycle, and studies climate trends to
aid in water resource management and understand long-term changes. It also helps mitigate the
impacts of floods, droughts, and phenomena like El Niño and La Niña.
 Hydrometeorology studies the interaction between atmospheric processes and water systems by
examining how weather and climate influence the water cycle, including precipitation,
evaporation, and runoff. It helps predict and manage water-related events like floods and
droughts, improving resource planning and disaster preparedness.
2.
 Groundwater: It is a source of water that is under the land surface. It is accessible by wells, tube
wells, and hand pumps. Found beneath the Earth's surface in aquifers, soil, and rock formations.
Typically, clean and filtered through natural processes, but can contain minerals like calcium and
magnesium. Used for drinking, irrigation, and industrial purposes; replenished slowly through
infiltration.
 Surface-water: This type of source is found on the surface of the earth like ponds, and rivers. Found
in rivers, lakes, reservoirs, and oceans. Easily accessible but more exposed to pollution and
seasonal changes. Supports ecosystems, human activities, and hydropower generation.
 Rainwater: It is the major source of water from rain. Freshwater from precipitation; relatively pure
but can absorb impurities from the atmosphere. Temporarily stored in cisterns, ponds, or on land
for direct use. Plays a critical role in replenishing surface and groundwater and supporting
agriculture.
 Groundwater is water stored in underground cracks and spaces within soil, sand, and rock, held in
aquifers. It can surface naturally through springs, discharge into lakes and streams, or be extracted
via wells. Groundwater supports surface water levels and can be pumped to the surface, though
shallow wells may dry up if the water table drops.
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Evaporation is the change of state in a substance from a liquid to a gas. In meteorology, the
substance we are concerned about the most is water. For evaporation to take place, energy is
required. The energy can come from any source: the sun, the atmosphere, the Earth, or objects
on the Earth such as humans. Example: Water evaporating from the surface of a lake on a sunny
day.
Transpiration is the process were water vapor escapes from plants through stomata, small
openings on leaf undersides. This process helps transport nutrients, cool leaves, and is influenced
by plant species and light exposure. Rapid transpiration can make leaves cooler than the
surrounding air. Example: Moisture released by trees in a rainforest, contributing to local humidity.
Condensation is the process whereby water vapor is changed into a liquid state. In the
atmosphere, condensation may appear as clouds or dew. This is also the process whereby water
appears on the side of an uninsulated cold drink can or bottle. Example: Formation of dew on
grass in the early morning.
Precipitation results when tiny condensation particles, through collision and coalescence, grow
too large for the rising air to support, and thus fall to the Earth. Precipitation can be in the form of
rain, hail, snow, or sleet. Example: A rainstorm replenishing water in rivers and lakes.
Infiltration is the physical process involving movement of water through the boundary area where
the atmosphere interfaces with the soil. The surface phenomenon is governed by soil surface
conditions. Water transfer is related to the porosity of the soil and the permeability of the soil
profile. Example: Rainwater soaking into agricultural fields, providing moisture for crops.
Runoff occurs when there is excessive precipitation and the ground is saturated (cannot absorb
any more water). Rivers and lakes are results of runoff. Some runoff evaporates into the
atmosphere, but most water in rivers and lakes returns to the oceans. Snowmelt running down
mountains into nearby rivers.
Water in the atmosphere moves quickly across the planet, while land and underground storage
depend on soil and rock types. Surface storage includes oceans, lakes, reservoirs, and glaciers,
while underground storage occurs in soil, aquifers, and rock crevices. example: Water stored in a
reservoir behind a dam for hydroelectric power and drinking supply.
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The troposphere is the densest layer, extending from the surface to about 12 km, containing most
of Earth's air, water vapor, and weather, with temperatures decreasing with altitude, from about
15°C at the surface to -60°C at the top. The stratosphere, (12-50 km), home to the ozone layer,
experiences temperature increases with altitude due to UV absorption, and is mostly cloud-free
with temperatures rising to about 0°C at its top. The mesosphere is the coldest layer, (50-80 km)
with temperatures dropping to -85°C at the top, where most meteors burn up and noctilucent
clouds form. The thermosphere (80-700 km) sees temperatures rise dramatically with altitude
due to low molecular density, reaching up to 2,500°C, and is where auroras occur and the
International Space Station orbits. The exosphere, (700-10,000 km) the outermost layer, has very
low-density particles that can escape into space, with temperatures exceeding 2,500°C, though
particles are too sparse to feel heat in the traditional sense.
Each atmospheric layer plays a vital role in sustaining life and regulating environmental conditions.
The **troposphere** provides oxygen and carbon dioxide for life, supports weather systems, and
facilitates precipitation, which replenishes water resources. The **stratosphere** houses the
ozone layer, which absorbs harmful UV radiation, protecting living organisms from sun-induced
damage. The **mesosphere** protects Earth by burning up most meteoroids before they reach
the surface. The **thermosphere** absorbs high-energy solar radiation, regulating temperature
and protecting life, while the **exosphere** marks the boundary between Earth and space,
supporting satellite communication and maintaining atmospheric balance.