Текст 4. Forms of precipitation

Задание 1. Прочесть, перевести.

The meteorologist makes an emphatic distinction between rain and rain showers.

Cumulus clouds produce showers; they last only a short time, usually minutes, bud the rainfall rate is heavy.

A large fraction of this rain runs off into rivers because soil cannot accept water at high precipitation rates, which often exceed 2.5 cm (1 in) per hour.

Steady rain is derived mainly from altostratus clouds associated with middle- latitude cyclones. If the mixed-phase process initiates the rain, the ice crystals melt before they reach the ground.

Rain usually persists for several hours, sometimes for a day.

The precipitation rate is low or moderate, perhaps 2 mm (0.08 in) per hour, assuring maximum opportunity for the water to sink into the soil.

In winter, when temperatures are below freezing in the whole atmosphere, the ice crystals falling from the altostratus do not melt.

They reach the ground as snow, the winter counterpart of rain.

The flakes form by coagulation of many ice crystals.

Snow showers also occur, mainly behind cold fronts.

Dangerous weather develops when raindrops or melted snowflakes fall through a layer with temperatures below freezing.

The drops then refreeze to form solid globes of ice, usually transparent, called ice pellets, sleet, or grains of ice.

Often they are not frozen solid when they reach the ground.

Interspersed, moreover, are drops that have barely started to freeze or consist entirely of water.

This mixture is freezing rain, a disastrous form of precipitation.

When it strikes cold ground, it freezes to form a solid sheet of ice called glaze.

Winter ice storms can breaks transmission lines and heavily damage forests and orchards by stripping trees of their branches under the weight of the ice.

Further, all transportation may be interrupted.

Snow pellets, also known as soft hail or graupel, fall in showers from cumuli.

Such showers develop regularly in the high mountains during the summer because temperatures are cold enough for the pellets to reach the ground before melting.

Often they precede and accompany mountain thunderstorms.

T

He pellets are circular or conical and consist of whitish ice particles formed when supercooled waterdrops coalesce with falling ice crystals.

Ice needles are long thin crystals forming on very cold winter days through sublimation, direct transition from vapor to ice.

As they float in the air, they provide a magnificent spectacle when the sun is shining on them.

Drizzle is a type of rain consisting of many very small particles with radii of less than 500 micrometers, it yields only traces or minute amounts of water.

Drizzle forms in very low clouds with a high water content but not subject to much, if any, lifting.

Relative humidity in the shallow layer below the cloud base near 100 percent prevents the small drops from evaporating on their short journey from cloud base to ground.

Snow grains are the frozen counterpart of drizzle.

Задание 2. Найти в тексте предложения, являющиеся ответами на вопросы:

1. What is the difference between rain and rain shower?

2. Do snow showers occur?

3. Why is «freezing rains called a disastrous form of pre­cipitation?

4. What is «sublimation»?

5. In what clouds does «drizzle» form?