April showers bring May flowers, so they say. This April is sure to be filled with rain showers, and much to the chagrin of those who want to set out the first pansies or pea seeds, as late as the 20th, according to the 2001 Farmer’s Almanac.

April is bound to bring every possible form of precipitation including rain, snow, sleet and hail. Even thunderstorms are possible in April. Technically speaking, of course, precipitation is any form of water, either in a solid or liquid state, that falls from the atmosphere and reaches the ground.

Some people can look at the clouds and predict when and what type of precipitation will occur. It is said that those harmless looking, streaks of thin white clouds that resemble horsetails mean rain will come in three days. On the other hand, no one would mistake the severity of the imposing, thick gray masses of a churning thunderhead and the imminent precipitation.

It’s no mystery what takes place inside a cloud. Inside the fluffy white masses, droplets of water grow larger and larger by merging with smaller ones through a process called coalescence. If temperatures inside the cloud are below freezing, raindrops actually begin as ice crystals. Both water droplets and ice crystals can coexist in the same cloud, and if conditions are right, water vapor can leave the liquid droplets and freeze onto the ice crystals. When the crystals stick together, a snowflake is formed. Precipitation begins when drops of water and or crystals become too heavy and fall to the ground.

Fog is not exactly precipitation, but it is welcome in spring. It seems to devour the snow, at first stripping down to the ground places where the snow layer is relatively thin, and, in time, clearing away where the winter wind blew snow to depths chest-high. The ground beneath that thick layer of insulating snow is rock hard. When the sun bears down, warming the ground ever so slowly, one can actually see the frost drawn out of the ground.

In fall, when the frost sets in, beautiful ice crystals emerge from the earth. In moist areas, it’s not uncommon to see these crystals “grow” to a height of a foot or so. On logging roads in the woods, or in the well-trodden paths of the field or pasture, it’s not uncommon to see little “ice cities” crop up. Frost crystals grow around the impression of a tire or animal track and look like miniature skyscrapers with intricately latticed designs of ice.

Naturally, like fog, frost isn’t considered a form of precipitation since it doesn’t fall from the atmosphere. When gardeners think of frost, they think of that glistening demon that strikes gardens in early summer and early fall, often damaging, stunting or killing precious crops in the early morning hours.

Frost is actually a cousin to dew. Dew, that moisture that sticks in tiny beads atop blades of grass in summer, isn’t considered precipitation either. Dew is condensed water vapor that occurs near the ground when the soil’s temperature drops below the air’s dew point. When prevailing temperatures are freezing, water vapor transcends its liquid phase and changes directly into ice. The white, delicate ice crystals that form on the leaves of plants are the same crystals that destroy tender plant cells.

As the ground warms, draws out the frost and awakens again with life, precipitation will fall and bring who knows what. Snow, rain, sleet, hail, drizzle or a combination of precipitation isn’t uncommon in April. Yet, bring what it may, the month’s displeasing weather is secondary to its rewards. As fog rolls in, drizzle runs down the windowpanes and the thermometer reading balances precariously at 32 F, the pointed leaves of the first tulip bulbs are poking up through the warmed soil on the south side of the house and, not far away, purple crocuses are in bloom.

Spring, at last, is here!

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@ctel.net. Selected questions will be answered in future columns. Include name, address and telephone number.